By-passing the normal WordPress template files

First, I normally don’t work on sites that use a “framework” theme because of the roadblocks I run into, such as my current question. However, I have a client who chose the Atahualpa theme, and I am loathe to ask her to switch because of my preferences. I know a lot of web developers do that, but I consider it bad manners unless there is a security issue.

So, my question is, with a WordPress theme that does not by-pass the normal WordPress template options by putting everything into functions.php, I can create a new template file that is specifically customized for a specific category. My question is whether there is any documentation on how to do this in Atahualpa. I tried a test file category-categoryname.php, but Atahualpa ignored it.

Thank you for your help!