ybin on second(?) revision iMac

[Nathan Hurst <njh@mail.csse.monash.edu.au>]

I've just been trying to get debian booting an iMac using a bootstrap
partition rather than the older method.  If I run ybin directly the
system refuses to boot yaboot, and after a short time(2 seconds)
defaults to MacOS. Option key doesn't show linux partition.  If I set
the boot-device to:
 boot-device hd:10,\\yaboot
then it boots into yaboot, but still no clickable icon.  Any ideas/suggestions?

galen:~# cat /proc/cpuinfo
cpu             : 740/750
clock           : 400MHz
revision        : 131.0 (pvr 0008 8300)
bogomips        : 797.90
machine         : PowerMac2,1
motherboard     : PowerMac2,1 MacRISC Power Macintosh
detected as     : 66 (iMac FireWire)
pmac flags      : 00000005
L2 cache        : 512K unified
memory          : 320MB
pmac-generation : NewWorld

Cc: replies to me please.