I am not using an existing theme - doing one for the site. My problem was not with modifying the theme, but with backend functionality in a file in the theme folder.
I have not used Wordpress for a while, and its probably just that the approach is different from what I am used to.
9:34 pm on Dec 7, 2013 (gmt 0)
You could make it a mini plugin. I usually leave layout related stuff in the theme and anything specific to the site that's not layout in a plugin for that site. The advantage there is that if you change themes the functionality doesn't go away.