sudo sh ./ati-driver-installer-11-11-x86.x86_64.run --buildpkg Ubuntu/precise
...but I've tried this on at least 5 different machines, and every time it caused problems. What worked for me was leaving off the buildpkg:
sudo sh ./ati-driver-installer-11-11-x86.x86_64.run
When the dialog pops up, select "All distributions" (or something to that effect), and then select the "Automatic" (vs. Custom) install.
Leaving off the buildpkg has worked every time for me. Oh, and make sure the .run file is executable before doing any of this.