ibook + USB hard drive = yaboot failure

[Michael Hrivnak <mhrivnak@hrivnak.org>]

Folks,

I want to install debian for use on my ibook on an external USB hard drive.  
The installation goes smoothly until it tries to install yaboot.  It fails 
with no explanation, and I can't figure out why.

I created the NewWorld boot partition as part of my manual partitioning, and 
it is the first partition on the drive.  All other partitions are part of lvm 
(home, root, swap).

I'm used to linux on PCs, so my knowledge of how macs boot is slim.  Can you 
help me diagnose this?  Hopefully it's a simple problem.  I've googled and 
searched this list's archives with no luck.

FWIW, this is the latest debian-ppc install cd with an ibook G4 and a 160GB 
external usb2.0 hard drive.

Thanks a lot,
Michael