OS9 is PPC only, and I don't believe any functional PPC Mac emulators exist for the Amiga/MorphOS. ShapeShifter/Basilisk emulate 68K Macs, and iFusion is a broken, bug-riddled mess - it won't work.
If you dual boot OSX 10.3 or 10.4 on it, though, you can run OS9 stuff through Classic mode.