The SCSI unit id is set via the jumpers on the CD drive itself - placement along the SCSI cable has nothing to do with it. You also need the SCSI device name to configure CD0. For example, Commodore's SCSI controllers use the name scsi.device. You need to find whatever name the Zeus board uses. Quick way is to hold both mouse buttons while booting to get to the early startup control menu. Then go into Boot Options - you'll see all your partitions on the right along with their device names and boot priorities. Take whatever name you see next to your boot partition - let's pretend it's zeusscsi - and use that name with CD0. By default, CD0 will have scsi.device, so change that to zeusscsi.device, or whatever popped up in early startup control. (Just remember to append the .device, which is not displayed in early startup control).
If you need to find out what unit number the CD drive is set to and you can't figure it out from the jumpers, change the icon info of HDToolbox to use zeusscsi.device, or whatever the name is. When you open it, it should find your hard drive and another device that it has no idea how to handle - that'll be your CD drive. Note the unit number and modify CD0 accordingly.
