Yeah, Mandrake hides the Root user on KDM to begin with. Its pretty stupid.
In LILO, type in the name of the Linux entry, followed by "init 3", like:
Linux init 3
and that will boot into Text mode where you can log in as root.
Once logged in, create another user with the "adduser" command.
Then you can log on through KDM as the user. To be able to see the root user on KDM (I dont recommend it), change that option in the "KDE Control Center" or "Mandrake Control Centre".