Honestly this is what I would do:
Source an A/T for the P chassis.
Swap the DE and VE between the B and P chassis, mating the CVT to the DE.
If the CVT doesn't operate as it should, install your previously sourced A/T. You'll need an ECU to drive the A/T. (Find a DE auto ECU)
Wish I could be more help. I don't know enough about how the CVT is actually controlled, though the mechanics are stupid simple.