Bare bones template included in another page

Here’s my situation: I am already using phpNews. If you know anything about that software, it’s a very simple setup where you just include a php tag in your page that defines which categories you want to show, and your news shows up in that location.

This is great for me because I have a pretty complex website template already, and I don’t want to have to create an entirely new WordPress theme to fit my site. So, is it possible to just create an absolutely bare-bones template that JUST shows the news items, and then include it where I want it?