I'm working on a G5 dual, Kona LH, and trying to work towards getting FCP 6.x running.
If I can remember correctly, here is what I have done:
1. I used an OSX 10.4.5 installation disk to do an "Archive and Install" procedure, choosing the option, "Preserve Users and Network Settings."
2. Then, I ran the OSX 10.4.11 upgrade.
3. Next, I installed a previous version of QT that will be compatible with the version of FCP I hope to run and compatible with the driver for the hardware I am using (in this case Kona LH). I believe the Tiger 10.4.5 install default was QT 7.0.4. I upgraded to 7.3.1, the closest thing to QT 7.3, which is what an AJA support staff member recommended.
3. Following the above, I updated the Kona LH drivers, which I believe get un-installed by the "Archive and Install" process. Kona LH Driver 5.0 is the version I'm now using.
4. Finally, I installed FCP 6. (I like how you can now choose where to put the media, btw.)
So far, after remembering I had to make proper settings in the AJA Control panel....I'm getting good capture and playback.