lionel 6-5906

No you don't need special track. Hook your red wire up to center rail on track from sound button and black wire from button to hot side of the transformer then run wire from outside rail to ground side of transformer. Your power will run thru the sound button to track to run the train. 

The sound activation button has a special circuit board inside it, which basically adds a little DC voltage to the track in order to trigger the horn to sound; depressing the button will cause the horn to blow. If you press the button and no sound is made, reverse the red and black wire connections.

On a side note, the "whistle" switch on the ZW will not work with modern sound systems unless it is depressed halfway. Unfortunately doing so will damage the silicon disk rectifier (the part that changes AC to DC to close the relay on postwar horns and whistles), causing it to eventually short out if used frequently.

Additionally most Railsounds cars had provisions for both horn/whistle and bell sounds. If your car is one of these, you will need to add a second sound activation button. The wiring diagram for this is available here; although shown with AF track and transformer the wiring does not change with 3-rail track.

-John