Developers of FireWire peripherals are required to provide device drivers. A driver for DV (digital video) is included in QuickTime.
The PowerBook G4 computer can boot from a FireWire storage device that implements SBP-2 (Serial Bus Protocol) with the RBC (reduced block commands) command set. Detailed information is available only under non-disclosure agreement; contact Developer Technical Support at dts@apple.com.
For additional information about the FireWire interface and the Apple APIs for FireWire device control, refer to the resources listed at "FireWire Interface".