Dunno, I've never tried to use my Catweasel in this fashion. Wild guess, but have you read up on project Arjuna? CAPS? I don't know all too much about either so it's a wild guess. I have used Catweasel with UAE to read and write Amiga disks, but only in a traditional manner. I mainly use my Mk4 to write D64s for the 128D, which it does in about 6 seconds flat.