It is theoretically possible to boot from a USB floppy drive, but I don't think the BP6 bios supports it (It rather predates the whole USB thing in the mainstream)
There's no SCSI flpppy afaik, as there's absolutely no point. What's wrong with the internal fdd connector?
As an aside, do you *really* need a floppy drive - I've not used one for over a year.