I came up with this solution last night. For your purposes, substitute your pre-August 2003 Mac where I say iBook, and your post-August 2003 Mac where I say G5.
- Install DiskWarrior 3.0.1 on the iBook.
- Shut down iBook
- Start up G5, if it is not already on.
- Connect iBook to G5 with a FireWire cable.
- Holding down the 'T' key, start up the iBook (in Target Disk Mode)
- After seeing the iBook's HD appear on the G5's desktop (or in the G5's Finder), restart the G5 and hold down the Option key.
- From the system picker, choose to start up from the iBook's HD.
- Run DiskWarrior 3.0.1 (from the Utilities folder in the Application folder of the iBook HD)
- After DW finishes, restart the G5 normally.
- Drag iBook HD image into G5's Trash bin to dismount that drive.
- Shut off the iBook and disconnect the FireWire cable.
[robg adds: I believe you need to order the CD for the newer machines as DW 3.0 was never able to boot them; the older machines just need a minor update and burn to be able to boot under Panther. I haven't tested this hint, so proceed with caution (as with any hint of an experimental nature here!).]

