Create a Left hand Navigation in Magento 1.4 1.4x for Modern theme

add the following to vert_nav.phtml

<div class="vertical-nav-container box base-mini">
<div class="vertical-nav">
<!--<div class="head">-->
<!--<h4>-->
<div class="block block-cart">
    <div class="block-title">
        <strong><span><?php echo $this->__('Categories') ?></span></strong>
</div><!--End block block-cart-->
<div class="block-content">
<!--</h4>-->
<!--</div>--><!--End Of head-->
<h4 class="no-display">
<?php echo $this->__('Category Navigation:') ?></h4>
<ul id="nav_vert">
<?php foreach ($this->getStoreCategories() as $_category): ?>
<?php echo $this->drawItem($_category) ?>
<?php endforeach ?> </ul>
</div>
</div><!--End Of vertical-nav-->
<?php echo $this->getChildHtml('topLeftLinks') ?>
</div><!--End Of vertical-nav-container box base-mini-->

Step 2
In app / design / frontend / YOUR DESIGN / YOURTemplate / layout / catalog.xml

<!--
Category default layout
-->
    <catalog_category_default translate="label">
        <label>Catalog Category (Non-Anchor)</label>
        <reference name="root">
            <action method="setTemplate"><template>page/2columns-left.phtml</template></action>
        </reference>
        <reference name="left">
<!--  <block type="catalog/navigation" name="catalog.leftnav" after="currency" template="catalog/navigation/left.phtml"/>-->
 <block type="catalog/navigation" before="-" name="catalog.vertnav" template="catalog/navigation/vert_nav.phtml"/>

NOTE: you are simply commenting out line 10 and adding line 11

Step 3

In in skin/frontend/YOURDESIGN/YOURtemplate/css/widgets.css

#nav { float:left; margin-top:15px; margin-left:15px; font-size:1.1em; }

/************** ALL LEVELS  *************/ /* Style consistent throughout all nav levels */
#nav li { position:relative;text-transform:uppercase; text-align:left;    }
#nav li.over { z-index:999; }
#nav a,
#nav a:hover { display:block; line-height:1.3em; text-decoration:none; }
#nav span { display:block; cursor:pointer; white-space:nowrap; }
#nav li ul span {white-space:normal; }

/************ 0 LEVEL  ***************/
#nav li { float:left; margin:1px 8px 11px 1px; padding:3px 8px; }
#nav li.active a { color:#444; }
#nav a { float:left; background:url(../images/nav_top_level_arrow.gif) no-repeat 100% 50%; padding-right:11px; color:#444; font-weight:bold; }
#nav li.over a,
#nav a:hover { color:#444; }
#nav li.over,
#nav li.active { margin:0 7px 10px 0; border:1px solid #bbb; background:#ececec; }

/************ 1ST LEVEL ************/
#nav ul li,
#nav ul li.active,
#nav ul li.over { float:none; border:none; background:none; margin:0; padding:0; padding-bottom:1px; text-transform:none; }
#nav ul li.parent { background:url(../images/nav_parent_arrow.gif) no-repeat 100% 50%; }
#nav ul li.last { padding-bottom:0; }
#nav ul li.active { margin:0; border:0; background:none; }
#nav ul a,
#nav ul a:hover { float:none; padding:0; background:none; }
#nav ul li a { font-weight:normal !important; }

/************ 2ND LEVEL ************/
#nav ul { position:absolute; width:15em; top:22px; left:-10000px; border:1px solid #bbb; border-bottom:2px solid #999; padding:3px 8px; background:#fcfcfc; font-size:11px; }

/* Show menu */
#nav li.over > ul { left:-1px; }
#nav li.over > ul li.over > ul { left:100px; }
#nav li.over ul ul { left:-10000px; }

#nav ul li a { padding:3px 0; color:#444 !important; }
#nav ul li a:hover { padding:3px 0; color:#5a7f00 !important; }

/************ 3RD+ LEVEL ************/
#nav ul ul { top:5px; }

    /**********************************************Vertical Nav ****************************************/

    #nav_vert { padding:0 8px; font-size:1em; z-index:999; width:180px; background-color: #F6F6F6; }

    /************** ALL LEVELS *************/ /* Style consistent throughout all nav levels */

    #nav_vert li {

    width:200px;

    list-style:none;

    position:relative;

    text-align:left;

    background-color: #F6F6F6;

    border-bottom-width: thin;

    border-bottom-style: solid;

    border-bottom-color: #CCCCCC;

    }

    #nav_vert li.over { z-index:999; }

    #nav_vert li.active { z-index:999; } /* to prevent the li separator from showing through on mouseover on li */

    #nav_vert a { line-height:1.3em; }

    #nav_vert a, #nav_vert a:hover { display:block; text-decoration:none; }

    #nav_vert span { display:block; cursor:pointer; color: #000; }

    /************ 1ST LEVEL ***************/

    #nav_vert li { float:left; background:url(../images/nav_bg.gif) repeat-x 50%; height:30px; margin-right:1px; }

    #nav_vert li.active a { color:#4c6a16; }

    #nav_vert a {

    float:left;

    padding:5px 12px 6px 8px;

    color:#4c6a16;

    font-weight:bold;

    font-family:Trebuchet MS;

    font-size:13px;}

    #nav_vert li.over a, #nav_vert a:hover { color:#CCCCCC; }

    /************ 1ST LEVEL RESET ************/

    #nav_vert ul li, #nav_vert ul li.active {

    float:none;

    height:auto;

    background:none;

    margin:0;

    }

    #nav_vert ul a, #nav_vert ul a:hover {

    float:none;

    padding:0;

    background:none;

    }

    #nav_vert ul li a { font-weight:normal !important; }

    /************ 2ND LEVEL ***********/

    #nav_vert ul {

    position: absolute;

    width:200px;

    margin-left:180px;

    top:0px;

    left:-10000px;

    border:1px solid #666666;

    }

    /* Show menu */

    #nav_vert li.over ul { left:0; }

    #nav_vert li.over ul ul { left:-10000px; }

    #nav_vert li.over ul li.over ul { left:100px; }

    #nav_vert ul li a { background:#FFFFFF/*#ecf3f6*/; }

    #nav_vert ul li a:hover { background: #F2F1D2; /*#d5e4eb;*/ }

    #nav_vert ul li a span { background:url(../images/nav_divider.gif) repeat-x 0 100%; }

    #nav_vert ul li a, #nav_vert ul li a:hover { color:#2f2f2f !important; }

    #nav_vert ul span, #nav_vert ul li.last li span { padding:6px 15px 6px 15px; }

    #nav_vert ul li.last span { background:none; }

    /************ 3RD+ LEVEL ************/

    #nav_vert ul ul { top:5px;}

    #nav_vert ul ul ul { left:-10000px;}

    #nav_vert li.over ul li.over ul ul { left:-10000px;}

    #nav_vert li.over ul li.over ul li.over ul { left:100px; }

       /* Fix for the IE bug */

    #nav_vert iframe {

    position: absolute;

    left: -1px;

    top: 0;

    z-index: -1;

    filter: progid:DXImageTransform.Microsoft.Alpha(style=0,opacity=0);

    }

Step 4

copy top.phtml from the base/defualt/template/catalog/navigation to your custom template folder ie app/design/frontend/YOURDESIGN/YOURDESIGN/template/catolog/navigation/top.phtml replace top.phtml

Edit your copy of top.phtml so it look like this

<?php
/**
 * Magento
 *
 * NOTICE OF LICENSE
 *
 * This source file is subject to the Academic Free License (AFL 3.0)
 * that is bundled with this package in the file LICENSE_AFL.txt.
 * It is also available through the world-wide-web at this URL:
 * http://opensource.org/licenses/afl-3.0.php
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@magentocommerce.com so we can send you a copy immediately.
 *
 * DISCLAIMER
 *
 * Do not edit or add to this file if you wish to upgrade Magento to newer
 * versions in the future. If you wish to customize Magento for your
 * needs please refer to http://www.magentocommerce.com for more information.
 *
 * @category    design
 * @package     base_default
 * @copyright   Copyright (c) 2009 Irubin Consulting Inc. DBA Varien (http://www.varien.com)
 * @license     http://opensource.org/licenses/afl-3.0.php  Academic Free License (AFL 3.0)
 */
?>
<?php
/**
 * Top menu for store
 *
 * @see Mage_Catalog_Block_Navigation
 */
?>

In other words delete all the active code.

Step 5

Add the category block to your home page.

lo on to the back end

CMS >> Pages >> Home Page >> design

in the Design Box paste this code

<reference name="left">
    <!--  <block type="catalog/navigation" name="catalog.leftnav" after="currency" template="catalog/navigation/left.phtml"/>-->
        <block type="catalog/navigation" before="-" name="catalog.vertnav" template="catalog/navigation/vert_nav.phtml"/>
</reference>

If you are getting errors about toggleMenu or if the menu appears but the pop out sub-categories do not work you are probably seeing the results of magento dropping support for toggleMenu.

as a quick and dirty fix you can paste:

function toggleMenu(el, over)
{
    if (over) {
        Element.addClassName(el, 'over');
    }
    else {
        Element.removeClassName(el, 'over');
    }
}

in at the start of js/varien/menu.js

Note this is not upgrade proof..

References / credits:
The original post can be found here where one Peter Hamilton provided most of the clever work at a time when people were just starting to come to terms with Magento.
From this post I extracted the complete solutions and created the original wiki entry here this has now been updated by Bill007 to 1.4 compatable and a lot of this post is based on his alterations.
Details how to create an upgrade proof installation by Joshua Barrie full details of which can be read here

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