Advice needed on AI's for a non-melee map

I would like to add computer controlled heroes to a capture the flag map.

Can i succed with an *ai file or do i need triggers for this ?

If i need triggers, can you give me a hint what approach or method i should use ?

If you know of a good tutorial on creating AI's for NON-MELEE maps, or i you have an existing map where i could take a look at the triggers, please let me know.

Thanks in advance