Don't know for sure but it should be feasible. This is done thru /etc/inittab:
Code:
# These are the standard console login getties in multiuser mode:
c1:1235:respawn:/sbin/agetty 38400 tty1 linux
c2:1235:respawn:/sbin/agetty 38400 tty2 linux
c3:1235:respawn:/sbin/agetty 38400 tty3 linux
c4:1235:respawn:/sbin/agetty 38400 tty4 linux
c5:1235:respawn:/sbin/agetty 38400 tty5 linux
c6:12345:respawn:/sbin/agetty 38400 tty6 linux
If you pay attention, only the 6th tty is enabled in runlevel 4. Maybe you'll get this done by inserting 4 in the other lines too.
Personally I prefer logging in in text and using startx to load the GUI.