I've been known to simply drill a couple small holes through the plastic trucks running fore/aft just inside the wheels and insert a piece of brass wire to rub on the inside of the wheels there. Solder a lead wire on after inserting the wire in-place.
Depending on how well you implement the idea, and how much pressure you put on the brass wire, it can work well, or work just OK and/or add a lot of drag. (Works well on my AccuCraft Goose, but not so good (too much drag) on a sound-equipped box car.) The advantage is that if you have any brass wire around, it is free to do.