You should just be re-starting the xsession not re-booting the computer. From the Kmenu choose logout when the window comes up choose login as different user. When you have the login screen you should see a menu option choose it and then the re-start xserver menu option to re-start X with your new settings. Then Log back in. Although I don't know if this works on the CD or not I run from HD.

If all it wants you to do is re-start the xsession and not re-boot your settings should take effect.