I'm not sure about the correct device and unit number in the sys:devx/cd0 mountlist. What should I be looking for?
It depends on the scsi controller/device you are using. I assume you already have a cdrom filesystem isntalled. So there should be a file like cd[0,1,2,etc] "sys:devs/dosdrivers". You can edit this file with a text editor. Look for the entries "device = xyz.device" and "unit = x". You should set "device = " to the device of your scsi controller (must be in sys:devs after you installed the driver) and the "unit = " to the scsi unit your cdrom drive is at (this is usually configured by jumpers on the device).. Which scsi controller are you using btw?