Can't change Home page template

I've been using the Atahualpa theme almost exclusively, and I'm very familiar with that - love it! But I was happy to see another great theme from you. The only problem I'm having with Montezuma is that I want a full-width slider on the Home page. When I create any other page and use the "image" template, I'm able to get the slider full-width. But even when I choose the "image" template for the home page, firebug tells me the #content class for that page is "col8." (I'm working locally, so I can't give you a URL.)

I've tried modifying the index.php file, but that doesn't appear to be the home page template.

Any suggestions?