With 3.2, the only thing you need to do to get a CD drive working is to adjust the tooltypes on SYS:Storage/DOSDrivers/CD0. For an A4000 with plain IDE it will be scsi.device and unit 1. Drag CD0 into SYS:Devs/DOSDrivers, reboot, and you’re done.
IDEFix is only for 3.1 (and older?). All newer OSes incorporate its functionality.