Dunno, but you can find more about the aux port in the Amiga CD32 FAQ:
part 1part 2Here I got the info how to make myself an RGB output for my CD32, and the information to make this adapter, too.
-edit- yes it's possible, but you have to find the pinout of ps/2 (and make sure you rewire that for instance the keyboard data pin of ps/2 will be redirected to the keyboard data pin of the aux port)