Need Help on how to use external CDR as cdtransport

I currently have an external CDR made by NEC model multispin 3xp. It uses SCSI-2 interface with the computer. THis appears to be an excelent drive and would make a nice transport, however, I could not find the digital out (which is provided with most internal cdr) to use with external DAC. Does anyone know how to get around this. Please help. Thanks.