Posted 11 January 2012 - 11:08 PM
I would to to Appearance -> Menus -> Screen Options and enable classes for nav items. Give a regular Home button a class of "home-image" or something.
Then you will need to upload a Home image into the Media Uploader.
From there its a matter of CSS. One way is to set the font-size to zero, and the background to your image and position accordingly.