X Session Configuration 

http://www.knoppix.net/wiki/Knoppix_Remastering_Howto

When testing X-based programs, you will have to

export DISPLAY=localhost:0.0

which will allow you to connect to your normal X session. Alternately (if you need to test window managers), you can create a nested X session. Outside of the chroot, run

Xnest -ac :1

Within the chroot, set your DISPLAY variable

export DISPLAY=localhost:1

Interesting stuff in /etc/init.d/xsession :

it ALSO sets background as /usr/local/lib/knoppix.gif