The complete instructions are here: http://wiki.cchtml.com/index.php/Ubuntu_Lucid_Installation_Guide
For Kubuntu just make sure that:
1) The proprietary driver is enabled/installed: alt-f2 and run jockey-kde (Additional drivers)
2) Add the X team PPA:
$ sudo add-apt-repository ppa:ubuntu-x-swat/x-updates
$ sudo apt-get update
3) Install the fglrx driver: sudo apt-get install fglrx
4) Initialize the ATI configuration:
sudo aticonfig –initial -f
In my case I’m using a dual monitor setup, and I did the above configuration and used the amdcccle configuration tool to setup the dual monitor. Please note that using Xinerama disables Desktop effects. If you want one large desktop choose the Multi-display Desktops. With this the desktop spawns the monitors and it’s possible to move windows between them.
If it fails to boot into graphical mode and/or it boots to VESA mode , go to safe mode and using the command jockey-text, make sure that the driver is enabled.
$ jockey-text -l
xorg:fglrx – ATI/AMD proprietary FGLRX graphics driver (Proprietary, Enabled, In use)
If the driver is disabled, enable it with the command: jockey-text -e xorg:fglrx