huh?Why isn't it an option for you? They're online and easily accessable, you can even use the 8100 drivers if you want. I know from personal experience that they work.
It's not hard. I was running catalyst 5.10 drivers and switched only after a blue screen reboot, which happened a few months ago during the demo as well. Install the old drivers, beat the game, then revert back to the new ones. It doesn't take that much time, and you can run it in DX 9 mode without any trouble.