On 1.6.2 here. All I had to do was put:
<block type=\\\"catalog/navigation\\\" name=\\\"home.leftnav\\\" template=\\\"catalog/navigation/left.phtml\\\"/>
on CMS > Manage Pages > Click on Home page > Custom Design (just like \\\"step 4\\\” above, but without changing the block template) and then delete <?php if (!Mage::registry(\\\'current_category\\\')) return ?> from left.phtml.
The menu is showing at home now and want affected for the category pages