Indeed it does everything I wanted. My main screen or video adapter is broken, so I used an external screen on my Macbook Pro. With this I saw the login screen but unfortunately I forgot my login credentials. To work around this I tried to get into the recovery mode to access the terminal to enter “resetpassword” to reset the password. Unfortunately I wasnt able to access the recovery mode because of the rEFIt boot manager. But as I saw the boot menue of the rEFIt, I was able to hit F2 on the apple logo and rEFIt showed me some boot options, among others “single user mode”. In the single user mode I was able to enter the commands:
mount -uw /
rm /var/db/.AppleSetupDone
reboot
After the reboot I was able to create a new admin user. As I logged in with the new admin user, I was able to reset the login credentials of my old account.
It worked, I’m happy :-)