I got it working. I logged in over ssh as "root" (you must have set a root password before you can log in) then I did:
ssh -X user@
password: live
sudo su
chmod uog+rw /dev/ati/card*
xauth merge /home/user/.Xauthority
export DISPLAY=:0
aticonfig --odgc --adapter=all
From then on it workes for me as "root" and also as "user"