To complete comments by Thomas:
If you must have the thing inside "real ROM" (read only memory), then it gets trickier. Often disk based drivers haven't been written in "ROMability" in mind and have data segment that they modify. This doesn't bode well with read only memory.
Thus, to be able to put these modules to ROM you'd need to "loadseg" them from ROM (InternalLoadSeg probably wouldn't do, since this thing must be done before dos.library is available), find the resident tag inside and add it to SysBase->ResModules.
Obviously for this to work the drivers in question must also behave correctly when fired up early on (before dos.library etc). For booting the driver must support adding the required dosnodes, and this doesn't sound very likely if the driver is disk based.
It can be done, and assuming the drivers meet the requirements, it should work ok.
CD32 drivers only work with CD32 and thus aren't that usable for generic CD bootability.
And indeed Phase5/DCE SCSI (at least the CSMK3/CSPPC/BPPC) support booting from CD, even coldboot.
