FS is not very backward compatible.  If you want something to fly right in a certain version of FS, it should be tailored for that version.

That being said, you should probably get FSX, since the Air Creation trike is in there.  It's basicly what you're asking for, and since it's a native FSX model, you wouldn't have to modify anything.

Although if you are wanting a specific aircraft to fly in FSX or FS9, you should get one that is specifically made for that sim.  Otherwise you wind up with compatability issues.

Getting an aircraft model to be compatible for another sim can only be done if the author of the original is willing to modify it for you.  Otherwise, you're kinda out of luck.