Just to add my data into the mix, I've tried using
Install Disc: MacBook (Core Duo) v10.4.6
Install Type: Customized minimal install
Disks: Two different 2.5" disks (one of which came out of a Mac Mini)
Enclosures: Two different enclosures (one which can use external power)
All without success so far. Gah!
I'll try DxQ partition reversal suggestion, just in case.