You can put any url you want in there, what it does is add a panic button in the lower right corner of every post so that if your boss sneaks up on you at work you can click it and it will take you to a different site, like
http://www.google.com/ (the google icon will be in the lower right of every post).
I guess there's some glitch in the hack that won't allow you to edit your options unless you switch on and fill in the url. If you do that, you should be able to change yourself to invisible, or turn signatures on or off.. all the stuff on that page should work for you.