Default-Kernel 2.6 instead of 2.4!

Hi,

im remastering Knoppix c't edition. I installed knoppix for remastering 
on HD and changed everything i need...including booting the Kernel 2.6 
as standardkernel from HD.
After burning the remastered Knoppix-Image, the default-image is still 
kernel 2.4!! Why?
I looked into the /KNOPPIX/boot.img with 1.44MB and found only the 
2.4-Kernel. Replacing it through the 2.6-Kernel didn't work, because the 
boot.img is to small for kernel and system.map.

How can I use Kernel 2.6 as default-kernel?!
I would be very happy if someone can help me :)
Greetings!
Manuel