The PTB system works because you roll it down (and up) like a 2-band tone pot. You have all the range to play with. Switching it in and out on a push-pull will only give you fully rolled off or out of circuit so no effect. You also already have the treble rolloff part already installed. You could perhaps wire in a bass cut.....but again its all or nothing with a P-P.
If you truly want the PTB system you would be better off buying 2 concentric pots and replacing the tones for both pickups.