I'd say it might be the scsi-patch of the ppc-board that vanishes your ide devices (it gives the scsi.device name to the real ppc-board scsi), but since you unplugged the ppc, it might be something else.
You should have something to boot from, and the CD-RW doesn't seem the appropriate one. Try an old ide-HD with the boot partition below the 4GB area (if you haven't one with the OS3.5-3.9 installed yet).
Another thing you can try is to plug the ide device, and boot from the floppies, using the install disk wich has the hdtoolbox program. Open it and see if it can read the firmware of the ide device, and its' geometry.
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Halfbaked
