If you have a PC with a parallel port >1MB/second like Toshiba 4060CDT/4080XCDT, Compaq Armada, Dell Optiplex, etc., you can try this out:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=320314504459It simulates any of the drives-- DF0:, DF1:, DF2:, or DF3:.
Currently, you can only select two of the four drives, but I may update the software soon to support all four drives simultaneously (if there's enough use for that feature).
Can you give example of some software that needs 3 or 4 drives simultaneously? Perhaps, I can get it for testing.