Carlos, sorry to disappoint you but I used it on my "Windows" PC :P
My guess is, since Pioneer is one of their major suppliers (A08 is the one used in the latest G5's I believe) for SuperDrives you will have no problem getting them to work - they should work out of the box.
One final dumb question, once you install the DVDRW drive, does it allow you to record DVD movies, or does that not work because the DVD is somehow copyrighted?
That's not a dumb question! Depends what you mean... Do you want to record your own DVD movies from AVI files i.e. with iDVD? If so, since your source and your own content is not encrypted it will work fine.
If you're trying to duplicate DVD movies that were bought, firstly on a eMac/PowerMac G5 you can only have one drive bay so you will need to copy it onto your hard drive or somehow have a second external optical drive. "CSS" and Region codes will apply and thus unless you use third party software like MacTheRipper to cache copies onto your hard drive while decrypting them (I am not at liberty to discuss further since cracking CSS to share DVDs and promote piracy is unlawful). IOW, as long as your source is unencrypted, copying will be fine.
One word of advice though; all DVD drives in the past 5 years or so, Mac or PC, burners or readers, come with what's known as RPC-2 firmware. This means you can only change the Region Code 5 times before the last change is permanently locked onto the firmware of your DVD drive (previously, RPC-1 firmware was used and you could just change a registry key or reinstall Windows to reinstall it). Again, touching on these topics is extremely touchy especially with the law. There are third party websites available that supply 'cracked' RPC1 firmware. The latest version I know of that this firmware exists is for the A08.