It may have changed now but back When I played it I needed to rename the .exe for it to UT3.exe then go into cataclyst control centre, click on gaming, untick the box labeled Use application setting on the Smoothvision HD Anti Aliasing and set to what you want.

No real idea but when I searched for AA and ATI I got this link.

You can probably do that by messing with some of the files, I think I saw a thread about this somewhere else so I suggest you google that.

Just go to AA settings under 3D in the Catalyst Control Center, select the option that says "Override Application Settings" and set it to your liking, you can do that with the Anisotropic filtering too.

Try renaming the exe to "bioshock.exe", "ut3.exe" or "oblivion.exe" and you should be able to force it on driver level.

" Is there a config.in file you can edit? Like when I wanted to use v-sync in borderlands I just changed the value of the line "Use v-sync" from False to True in one of the config files. "

There should be an "override AA" option in the CCC, just look a bit closer. Alternatively you can use RadeonPro. 

" @Khemitude:  yes i found it  and increased it to 8x anymore gives a really annoying blur to everything, Thank you all for posting helpful tips :P "

YOU CAN PLAY ARKHAM ASYLUM IN MASS EFFECT?