SicilianFalcon - to design AI flights I think you need TTools and AirExTT (you can get them on FS download sites). I have them both because I wanted to create my own flights but haven't done that yet

All my additions (AI ones) have come either from FSTraffic2002 or ones I have installed from Project AI.
I think you can assign any aircraft, of any airline, to any flight you want if you create a flightplan first. I am still hoping to find "work" for my little ERJ145 with the tartan tail.
Sabena and Sobelair - gone but never forgotten.
Louise