For a Gen I, it might be that easy, but for Gen II it isn't, as it is in one of the options (Vehicle), press reset to turn it off. I am going to use an Arduino to do it for me (automatically 5 seconds after turning on), along with other things.
I have a simple 555 circuit for my 2000 Grand Marquis (it waits 5 seconds, then there is a 1 second 12v pulse) but on that car a normally closed button in place of the push button can also be used (but 04 and newer it requires a pulse and not a constant 12v).