Dunno if this helps:
Where it says you need to be a 'super user' just prefix the command with sudo and then put in your password when asked for it.
---------- Post added at 15:09 ---------- Previous post was at 15:09 ----------
Oh, and that was taken from:
http://www2.ati.com/drivers/linux/linux_8.16.20.html
You may need to tweak it a little if you're using a different version of the driver, but they should all have their own installers.