Keep in mind that the Pismo can boot from USB. it might be slow, but boot from a USB HDD. Also try putting the disc in the mini and putting the Mini in FireWire Target Disk Mode. I have seen optical drives from a mac in FWTDM show up in another machine as it just forwards as if it's a FireWire disc drive.

So you have two options, USB DVD/CD or FireWire Target Disk Mode on the Mini, then boot off the DVD drive on the mini. Simple as that!

EDIT: Thought you said Mac Mini. Got another machine with FireWire? Even an intel mac should work, as long as you can use the other machine in FWTDM. It should work