the mdl file is 100% compatible with fs2002. 

the an124.air is a copy of the default boeing747 so you 
can use the fs2002 version of that file.

the aircraft.cfg was an 747-400 one too, but was modified
to get the an124 heavy feeling and dynamics. you can open 
the 747 aircraft.cfg into any editor and copy/paste the
modified lines of the fs9 an124 aircraft.cfg into the 
fs2002 version. 