I have a G4 500Mhz Bi pro with ADC output (bought 16 months ago) and I installed succefully Pioneer DVD driver.
I burn al ot of DVDs using IDVD both uner OSX and Classic.
it works fine.
NOTE:
the problem is to find the software:
I got it when a purchased a new brand 1000 mhz bi pro with...
I used macosx public beta On my G4 45O Mhz MP; firewire works regularly WITHOUT any addtional instllation with my LACIE 20 GIGA external disk.
hope this help.