The regular way of saying it would be:
"From now on, ending a sentence with a preposition is something I will not put up with."
But 'with' itself is a prepositon, of course, so he just goes out of his way to rephrase the sentence in such a manner that it no longer ends in a preposition; but does so in an awkward, be it still grammatically correct, fashion (for giggles). The normal way to do so would be:
"From now on I will not put up with ending a sentence with a preposition."