Yes it's an pc XFX 4890 (regular stock clocked model; not XXX version). I have it working in osx via injectors. I've been trying to flash it recently, as a rom has become available, however things aren't going very well... 😟 It seems possible that my later version xfx 4890 is not very compatible with the rom. Seems like people with earlier versions, had better success.
If I can't get it to flash correctly, might just change to a more compatible brand.
This thread can help answer all your questions:
http://forums.macrumors.com/showthread.php?t=713428
http://forums.macrumors.com/showthread.php?t=751062
Word to the wise though, if you're not comfortable fiddling around with stuff inside your comp, it might not be a good idea. It can cause a lot of headaches~