I have to agree. Spraying it into the spark plug holes won't do much for your intake valves in my opinion. Not that I'm recommending it, but it would be more efficient to spray the stuff into your intake tract just before it hits the intake valves.
As far as cranking an automatic without the plugs in...you would be cranking it just like you are trying to start the engine any other time.
The chemical is meant to soften carbon deposits over that 6-12 hour period. Then when you crank the car, it blows that stuff out the exhaust...chemicals and deposits together.