if you don't have a set of workbench disks, this could be one solution.
If you have WB3.0 disk set, you can use these to install a workbench on your A4k. You can use crossdos (pc0:) to access pc formated disk to tranfer a cdrom file system. After installing set device to scsi.device unit 1 for slave cdrom. Now your cdrom should work!
should even work with wb2x quite similar
