Category for a module generated site

Hy!

I created a module, that shows a generates a special site when browsing to the URL defined in the hook_menu() function.
As I do some layout in dependence of the current category, I also want to assign a category to this module generated site.
But as it is a module generated site, and not a "page" or "story", I can't assign a category to that site.
Is there nonetheless a way to assign a category to that module generated site?

Kai