It is now working fully (only 1 DVI display though. My HDMI port does not work at all under Mac OS X. I've ordered a Display Port to DVI adapter and will see if that port works once I get it.)
Zeus worked great for me in that it was able to modify my ROM file and also turn off the power message. However, the downloaded drivers from Zeus did not do anything for me, nor was it able to flash my card. I eventually had to go the DOS route.
After several hours of playing I was finally able to get QE to function properly. I used Zeus to download and install the drivers (and then repaired permissions). But that didn't work. Then I found a thing called "ATI10.6.4Patch.pkg" and installed that (and repaired permissions), but that didn't work either. Then I found a distribution of "mapp" with Kext Helper b7. I used that to install all the extensions that came along with it (and repaired permissions). That gave me QE acceleration but along with it came serious screen glitches. Finally I found the "Ny mapp" distribution and installed those extensions (and repaired permissions). And THEN IT WORKED. This is great.
BTW, I think this is a great marketing opportunity for someone here (with time). If you could just get the driver process streamlined and working properly, you could sell pre-flashed cards with a nice driver set on CD. Or alternately you could flash cards that were sent to you for a fee and send them back with the drivers (well, the kexts anyway).
In the end it took me many hours to finally get this working. I would have been very happy to just buy a good pre-flashed card (I know there are some supposedly on eBay, but I wanted a 4890 specifically because I also game in windows, so within reason my card really needs to be as fast as possible at the time of purchase.) I don't know what a fair markup would be since you would have to maintain something like Zeus to update drivers after most major or minor OS update. Maybe $50 or $75?
Thanks again for all the hard work. I'll finally be donating!
(When you gonna get those new 6000 series cards working? )