I really don't know the steps involved in this, but the first thing you need to do is get the parallel port SCSI emulation going. You might find some help at tldp.org in the sections on parallel port ZIP and JAZZ drives.
Next you've got to get xsane to see that printer. I don't remember if the xsane docs say anything about working with parallel port scanners, but they might help too.
Finally, there is a list of what scanners xsane supports. The 1220 sounds familiar, but I know the USB scanner I had was the one model by that manufacturer that wasn't supported.