IMHO there's only one possibility to attach a scsi-cable: look at the upper right corner of the mainboard. There are three rows of scsi-terminators, mostly not fitted. Get a SCSI-cable, some pins and solder the wires of the SCSI-cable to the pins that will fit in the holes of the SCSI-terminators.
On a Falcon, you should obtain AHDI 6.061- the latest version -.