The MTH Passenger Station and Platforms require 10-14VAC, so you can use the Lionel plug and play if you are powering the system at these voltage levels. If you are powering it off track command voltages (18V or higher), you should not use P&P with the station.
Use the red and black wires in the P&P cable. Polarity does not matter here. The white wire is only used if you are operating an accessory with an insulated track section.
Here are links to the P&P wiring manual, MTH Passenger Platform manual, and MTH Passenger Station manual. The Station manual neglects to specify the supply voltage, but it will be the same 10-14V as the Platforms.
Bob