I don't think the DHzer0point 0.64 driver will support any R600 cards.
...But this one might do it : DHzer0point 0.69 ;)
http://www.driverheavendownloads.net/zeropoint.htm
btw...
I have called ATI support (GER) yesterday and tried to find out, if the resolution is limited by the drivers or not.
2560x1600 in dual link mode ist the max res those cards can do with Catalyst.
"what, if i use other drivers like omega or zeropoint?"
The guy was like this: "YOU SHALL NOT USE OTHER DRIVERS BESIDE THE REAL ONE" :D, but he also said it might be possible and I will recive an email, when he finds out something about this...
1 day passed and no answer.
same with Matrox, but I have only sent an email to them.