Imation has posted an update for their USB SuperDisk drivers. Version 1.1 of the drivers fixes a bug which caused most multi-floppy installers to fail.
The drivers cause the Imation USB drive to assume the drive number 2. This is normally used by an external Macintosh floppy disk drive. When the drive number is 1 or 2, most installers that use multiple floppy disks will now work.
Remember that the Imation USB drive should be disconnected from the iMac when you install the drivers.