I haven't needed to replace my AOS, so I haven't used any of the following, but they may be helpful (especially the first one, done by a seasoned 986forum member who, far as I can tell, seems to know what he's doing

):
http://986forum.com/forums/showthread.php?t=18090
http://mike.focke.googlepages.com/airoilseparatorreplacement
The guy at this site slightly modified Brad Roberts approach. I didn't really closely read what he did, so I can't attest to whether it makes any sense or not:
http://www.babblers.org/forums/showthread.php?t=10421
Good luck. Let us know how it works out.