What aircraft are we talking about, here? If it has the usual folders for FS2002, then they should work if you stick them in the aircraft folder. If not, then modify the aircraft folder to conform to FS2002 standards.
747-400 folder:
model (folder)
panel (folder)
texture (folder)
sound (folder)
aircraft.cfg (configuration file)
boeing747-400.air (aircraft config file)
boeing747-400_check.txt (optional text file)
boeing747-400_notes.txt (optional text file)
boeing747-400_ref.txt (optional text file)
If all those folders and files are in the aircraft's folder, then it should work in FS2002.
Of course, I may be misunderstanding your problem. If I am, then I'm the idiot, not you.