ibook + USB hard drive = yaboot failure

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

G5 single (PowerMac 9.1) status.

I have been looking through the Ubuntu forums of late and it seems like the problems that have dogged iMac G5 and G5 single users (thermal control and sound) are still there in Dapper. As it seems that the only work around for the issues with the CD drivers (Sarge PPC) and USB keyboard (Etch PPC) w