Problem installing debian: netinst hangs at "Loading ramdisk..." on an IBM 7028-6C1

[Bart-Jan Vrielink <bartjan@vrielink.net>]

Hello,

I'm trying to install Debian stable on a IBM Pseries 610 using the 
netinst Cdrom. After some fiddling in the SMS I end up with a yaboot 
prompt. No matter what I try (tried expert64, install and also expert64 
with the video=ofonly option) but I get nothing more than:

boot: expert64
Please wait, loading kernel...
   Elf64 kernel loaded...
Loading ramdisk...

What am I doing wrong? Does Debian support my system? To what console is 
Debian and kernel sending its output?