Hi vijirin
I you want you application to run after the kde desktop is running
the easiest is to place a script in the folder:
/home/knoppix/.kde/Autostart

Note that a directory like .kde is hidden. Choose view hidden files
to view it.

To get rid of items in the task bar you may use kde functions
calls with dcop

I assume you are talking about making a live CD

I have a script to clone knoppix to a new CD DVD that you may want to test.
It has a feature to place scripts and application links in ~/.kde/Autostart
http://grow-knoppix.berlios.de/

Best Wishes
paradocs