Lots of info on Aminet for setting up and mounting Zip and CD-ROM drives, both SCSI and IDE.
http://wuarchive.wustl.edu/pub/amine...ring=zip+drive
EDIT:
Also I've found a few pages on the Squirrel SCSI interface as well on google.
http://www.google.com/search?sourcei...uirrel+scsi%22