What you will do, as a matter of fact, will be changing is pleasure area. He will have to learn to transfer all the pleasure he thinks he has only in his dick, from the top of his penis, to his anus.
After a while, you will get to make the anal pleasure his only way to get sexual satisfaction. And you, will get this way all the power and the control you wish on him and much, much more pleasure.
Because, in exchange of the pleasure he will get from your strap-on, he will feel the impetuous need to give you all the pleasure you may want, and will do anything to make you happy. He will be “programmed” to satisfy you.