ptreves, you must be a rare breed, most people find it essayer to find the command line (by total accident), then it is to use it
heres the overly hard (yet only way i can tell you .. as we all need to know more about WHAT desktop you use (kde, gnome, or "other") ...
and here it is!: pop a live linux cd into the cdrom drive, set boot from cdrom, once you are on, mount and chroot into your system (after seating up, and loading the required modules for the kernel on the cd)
then go pluck away ... tho this way is not recommended, unless its an emergency, as it just takes so long (boot, reboot, boot, reboot!) ... and a few other minor things .. but if you install from binary, then there shouldn't be any problem at all
"the other way" :::
if you are lucky just press (ctrl alt del) and prey to the penguin you don't have a *dm service running (or prey it crashes)