Change MAC address?

I have a problem, I would like to change the MAC address on the mini2440
but I can't get it working. I use u-boot and the command "set ethaddr
08:00:2f:00:00:02" and saveenv, but if I change the MAC in that way, I
can't get any network connection anymore in debian. 

I think the MAC needs to be changed in u-boot, but how? Is it possible to
change when it already is compiled (u-boot running) or do I need to compile
it with different settings? u-boot/drivers/net/dm9000x.c seems to be the
file for the network card, but I can't find any mac address there.

Does somebody know how to change mac address with u-boot? I've searched the
forum and googled but can't find a solution..

http://groups.google.com/group/mini2440

4th topic down . . . maybe