And, yet another way to "bypass the GUI", you can log directly into the console by using the login window. Press the down or up key on your keyboard and press option-return -- in the name type >console and leave the password blank. Click login, or press enter.
Login as you otherwise would, when you're finished just type in exit and press return to come back to the login window. This and Terminal.app are not the same as single-user mode, however.