If a graphics card is not explicitly supported by Apple/did not come with your Mac setup by default, we do not support our software running on this card either.
As far as Mac OS X goes, we only test on default Apple approved & supported GPU systems. The combinations to account for with modified Mac setups unfortunately exceeds well beyond our QA resources. If you have a modified Mac system and are confident your system should be able to use our products, you are free to use a trial installer and test things out on your system. You are even free to contact Support if you run into issues, but know that-- because we haven't tested on your setup-- that any issues you run into may not be resolvable if the source of the issue is that innate, untested for unsupported setup.