The file /etc/yaboot.conf can be edited to change the booting behavior of your PowerPC Linux machine.
Edit the file with root privileges:
sudo nano /etc/yaboot.conf
After editing and saving the file, you must run this to write changes to the boot partition:
sudo ybin -v
To have more boot menu options include these lines in your yaboot.conf:
To have yaboot default to booting to OS X include this line in your yaboot.conf:
To change the colors of the yaboot screen include these lines below. Alter as desired. These settings below create a color screen similar to the OS X open firmware colors.
To boot into single user mode type this at the yaboot prompt: