I once tried to change that on CrunchBang 8 also Ubuntu based with setting the minimum login number to 0
and changed also other entries , but in the end I had dialog(whiptail) running saying some obscure permission things , which I could bypass by another tty ,
but somehow I did not boot that installation a long time and when I tried it again , nothing worked anymore as expected .
It is possible to get a root screen on another tty from the menu @Xubuntu10.04 but I can not remember exactly anymore .
In fact I had a problem running firefox as user , because firefox had no write permissions in my username HOME directory . Took me quite a while to figure that out .