Do the following as root:

1. Downloaded 

      ati-driver-installer-8.24.8-x86.run

   from somewhere.

2. Ran it

   bash$ X_VERSION=x690 sh ati-driver-installer-8.24.8-x86.run

3. It fails.  Get the following two patches:

     ati-drivers-8.22.5-intermodule.patch
     ati-drivers-8.24.8-noiommu.patch
 
   from the mactel mailing list.  (Thanks to Gimli!)

4. Apply the patches:
     
     cd fglrx-install/common/lib/modules/fglrx/build_mod/ 
     patch -p0 < exact/path/to/ati-drivers-8.22.5-intermodule.patch
     patch -p0 < exact/path/to/ati-drivers-8.24.8-noiommu.patch
     cd ../../../../../

5. Try running the install again:

     X_VERSION=x690 ./ati-installer.sh x --install

   The "x" there seems neccesary, but I'm not sure why.
   Also say "no" to launching a web browser.  This time
   through it should work.

6. Test that it works:
    
      modprobe fglrx
      dmesg