Simple. Mac<->PC<->CD-ROM. The Mac has an internal hard disk which terminates
one end of the SCSI bus. The CD-ROM drive has a SCSI terminator, which
terminates its end of the bus. I just load my CD-ROM device drivers onto my
Mac and my PC, and they both happily read the drive.
I didn't know it was that simple. <grin> I didn't think the PC and the MAC
would like each other on the same bus. What SCSI card are you using on the PC
side and what CD-ROM drive are you using?