You will almost certainly need TTools by Lee Swordy to install AI into FS9. There are many low-poly AI aircraft out there, but they need flight plans etc to run in the sim, and that’s the tricky part.

I’m now starting to get into AI stuff, but already finding out how difficult it can be. I have a reasonable knowledge of how the AI works, but I’m trying to Get a Russian Navy Tu-142 “Bear” to fly through the Baltic, down through the UK Iceland gap for interceptions by my RNoAF F-16 and RAF Tornado F3/Typhoon. Direct flight from Murmansk to Keflavik is the nearest I’ve got so far! 😮