I've also described the steps to install catalyst 11 on xubuntu 12.04.
Take a look!
Complete Guide To Mine Bitcoin on Xubuntu 12.04
http://goo.gl/vP3G9
First you will need to download the drivers from the AMD archive, you can try to wget it, but for some reason I have problems with that so I just download through a browser.
http://support.amd.com/us/gpudownload/windows/previous/11/Pages/radeon_linux.aspx?os=Linux%20x86&rev=11.11
Chmod +x the download to make it executable (chmod +x ati-driver-installer-11-11-x86.x86_64.run)
Enter super user mode by using sudo before each of the following lines......or make life easy and just use sudo -i to get a root prompt.
(sudo) sh ./ati-driver-installer-11-11-x86.x86_64.run --buildpkg Ubuntu/precise
After a couple of dialogs it will finish and you should have three new packages in the directory.
IMPORTANT: It is vital to run this next command and let it error out!!!!!!!!!!!!
(sudo) dpkg -i fglrx*.deb
This step is needed or else the software installer in the next step will just download and install the latest drivers and SDK instead of repairing the dependency cache issue.
Navaigate with the file manager to (fglrx-amdcccle_8.911-0ubuntu1_amd64.deb).
Right click and open the file with the "Ubuntu software manager".
The software manager will indicate the install has a dependency cache error, click the repair button to have the manager repair the cache. Walk away have a soda, beer whatever..it will take a few minutes.
When finished, the manager will indicate it is installed.
You are finished with the install...that is it, everything including the SDK is installed.
Just remember to do (sudo) aticonfig --adapter=all --initial and reboot to get the Xorg configuration set with the ATI drivers.
PS.... Don't forget to export DISPLAY=:0 and export GPU_USE_SYNC_OBJECTS=1, in fact just put those in a script along with your miner start up.
Hope this helps somebody out and avoids hours of frustration...I have personal experience ...
+1