[Grml] jmicron network card driver installation fails

hi there, I'm running grml with a 2.6.26 kernel on an asus eee box b202 which has unfortunately a JMicron network card. I want to install the driver (ftp://driver.jmicron.com.tw/jmc2xx/) manually because the driver is not included. As mentioned in the readme .txt I did:

apt-get install linux-source-$(uname -r) apt-get install linux-headers-$(uname -r) apt-get install build-essential

After 'make install' I got the following error:

make: *** /lib/modules/2.6.26-grml/build: No such file or directory. Stop. make: *** [all] Error 2

Any suggestions? By the way I'm trying this on a virtual machine because with the same grml image (because the asus eee box has no internet connection :) )

Thanks a lot in advance!

Best, Grischa