I run mostly postwar engines, and I use the cab-1 controller. What you need to make it work with your ZW or KW is a Powermaster and a Powermaster cable (can’t recall what Lionel calls it, it’s about $15 I think) for each throttle you want to use, and the cab-1. One cab-1 will work with multiple Powermasters, but you can use multiple cab-1s if you want to let two people run 2 trains for example.
The powermaster cable hooks up to you transformer where your track currently does. Then the Powermaster plugs into the cable. Then you hook the track up to the two screw terminals on the Powermaster.
After you get it all hooked up, you need to program each Powermaster, which assigns it a number from 0 to 9. I don’t recall the specifics, but it’s about a 1/2 dozen keystrokes on the remote, and flipping a switch on the Powermaster unit.
Once the Powermasters are programmed, you’re ready to run trains! You press the button on the remote, what number Powermaster you want to control, and then turn the knob. (don’t forget the transformer lever has to be turned up to an appropriate voltage)
Things I’ve picked up over the past few years of using this setup is:
Adding a lighted LTC lockon made the sound buttons a bit more reliable.
Using the bell button sounds the postwar whistles better than the whistle button.
You can adjust the throttle on the ZW to a lower voltage to limit the maximum speed if little ones are going to play with the remote. I usually set the handles to about 18 volts, but lower it to about 12 when little hands are involved, especially if newer can motored engines will be run.
The Powermaster cable has an inline fuse holder in it. Get some extra fuses (don’t recall the size, perhaps 7.5 amps?) for it
This method runs the trains the same as using the throttles on your ZW, meaning it varies the voltage going to the track. It doesn’t allow you to vary the speed of multiple