This method is still time consuming but it works for me. Get a copy of transdisk and a pc file splitter program - I've got a nice simple one that I could email to you. You'll also have to use the Amiga shell program called join.
Yeah, before I resorted to this multiple disk swapping method I was trying to compress adfs with LHA - on an A600 with 2 megs. Never again...
:-)