Note: I got this from somewhere.

To bypassing Aqua involves manipulating the file /etc/ttys. We’ll open the file up in the pico editor. To do so, enter the command: sudo /usr/bin/pico /etc/ttys. The file will open in pico and you should see something like the following:

#
#      @(#)ttys        5.2 (Berkeley) 6/10/93
#
# name  getty                          type    status          comments
#
# If the console is marked insecure, single-user requires
# the root password.
#console        "/usr/libexec/getty std.9600"  vt100  on secure
console "/System/Library/CoreServices/loginwindow.app/Contents/MacOS/loginwindow"

Notice the two lines that start with the word “console”? The first one is commented out, which means that the second is used. The second loads the LoginWindow. To bypass LoginWindow, comment out its line by preceding it with a # mark. The pico editor does not wrap the line, so be careful that during your changes parts of the LoginWindow line don’t get pushed down to the next line. If they do, use backspace to move them back, being careful to maintain white space.

Now uncomment the first console line. You’ve now switched which of the two lines is commented out. Save your changes by pressing Ctrl+O, then Enter, then Ctrl+X. Reboot your system and you should now see your system’s complete boot process and then be presented with a standard BSD-style login.

To resume using the normal login interface, swap the two console lines in /etc/ttys again.