APMap vs GUID - will this work?
 

What I want to do is make a full backup of a G4 PPC running Tiger onto an external hard drive, and then use the files on that external to help set up a new Intel Mac Mini running Snow Leopard. If I can limit Migration Assistant to certain files (like iPhoto, Mail, Network settings) then I'll use that, otherwise I'll move most of the data manually from the external to the Mini.

What I want to know is this:
Can I make a full backup from the PPC to a hard drive formatted GUID? I don't want to boot the PCC from that back up - I only want access to those files from the Intel Mini.

After the Mini is set up, I'll want to use the external for SuperDuper backups, so then the obvious choice will be GUID, so I was hoping to format the external only once.

If it matters, the external is a Seagate SATA in an OWC enclosure with Oxford 934, USB2 and FW400

You can certainly make the copy, yes: Tiger (10.4.6 or later) should know about GPT/GUID partitioning.q