@motorollin
You'd think this would be the case. Essentially the moana cdrom is like a kickstart ROM. Once it's loaded, it looks for bootable media, such as (in the classic kickstart in a ROM sense) floppies or hard disks, and I guess now cdroms.
So I would guess that so long as you could install OS4 to hard disk, you'd just need to have the moana cdrom in the drive to boot.
The next question is, does OS4 provide functionality to eject the disk? Booting from a hybrid moana + OS4 install cd, would probably result in _alway_ booting into the install environment.
Leaving the moana cdrom in the drive permenantly kind of rules out using that drive. Does OS4 running on MacMini support other drives, such as USB DVD-ROM drives? In that case you could just leave the moana cdrom in the internal drive, and use an external drive.
These are all very pertinent questions. Of course without AOS4 install cd, a suitable macmini, moana files and the know how of making a hybrid cd image, I can't be any more help

tiffers.