Mike, adding the line
macosx=/ht@0,f2000000/pci@3/k2-sata-root@c/k2-sata@0/disk@0:8
(8 is my OS X partition number. It's probably different for you) to your /etc/yaboot.conf and then running ybin should let you boot into OS X.
Mike, adding the line
macosx= /ht@0,f2000000/ pci@3/k2- sata-root@ c/k2-sata@ 0/disk@ 0:8
(8 is my OS X partition number. It's probably different for you) to your /etc/yaboot.conf and then running ybin should let you boot into OS X.