I am one of the guys on XLR8 that flashed my Dualcore G5 DVR-110D to a DVR110 to enable DVD-RAM write (as purchased would only read). Works good.
I first used DVD-RAM with my LG-4163b in my G4. At first, I was just curious but once you use it, you will need it. Its awesome, basically a 4.7GB floppy drive. No need to burn anything, just drag and drop, done.
The caddy style DVD-RAM discs are the old style. The newer ones are all bare discs, if you can't find any, try the dvd section of the electronics stores, many of the DVD recorders use these discs. Maxell work really good in my G5. Get 5x if possible.
The big problems you have are that you need something to flash the drive. In my case, DVRFlash is available to do the deed. Second, you need the DVD-RAM capable firmware. I found these for my machine at
http://forum.rpc1.org
The big problem as I understand it is that the firmware is all PC code, so unless you have a mac application to use that code, there is no way to update it in your computer (maybe VPC but scary). IE, I used PC firmware and DVRFlash which was written to flash the firmware on Macs using that code.
Check out the forums, maybe comeone there can help.
I don't understand why DVD-RAM isn't more popular, it is awesome!
If you have any questions, I will try to help but understand beyond actually being stupid enough to change my drive family (110D->110 is a different family) and take the risk of frying my drive, I'm not a computer expert.
later
Tim