Apple has posted PowerBook Firmware Update 4.2.9 which is only for 550MHz or 667MHz PowerBook G4 computers running Mac OS 9.1 or later from a local drive.
”If you are using Mac OS X you must boot from a local Mac OS 9.1 writeable partition (not a CD, or network disk) prior to following the update instructions. Firmware Update 4.2.9 includes improvements to Firewire target disk mode when running Mac OS X, and improves starting up on systems with 1 gigabyte (GB) RAM and enables Netbooting over gigabit Ethernet.”
