You used ot be able to mod the respective cards over to quadro and firegl. They are the same architecture, just a different set of drivers for the card. Haven't seen any psot on how to do any of the cards lately.
If you can find a comparable Radeon and FireGL pairing (same processor and memory), the right ATI flash utility, the right FireGL BIOS, and all of the stars in the heavens are aligned, you can get it to work.
You are also, just as likely, to make your own custom paper-weight. If you want to experiment, then I say geek away and give it a shot.
If you really want a FireGL, they can be had for cheap via eBay and Craig's List from time to time.
Regardless, good luck and may the Force be with you! HOOAH!!!