Basically I'd like it so that I could arrange categories and sub-forums to display within forumdisplay as they would if they were on the index. Is this possible?
What exactly do you mean?
Basically how vBulletin (at least 3.x version) displayed sub-forums in a category.
see print screen - this is what is seen within a forum off the index. 'National index' is a category, 'Paris, France' is a forum within that category.
Could this be done with just a bit of template modification? Or would it require a mod to draw the information from the subforums?
Nope?