I just use an old axle stub as well. Works great. You can also use a cordless power drill too if you need something to take to the track. I find it gives a more uniform finish on the tire than using a belt sander or dremel.
Edit: No one makes a slick tire (Except Panther, which don't seem to work anywhere I've been to). It also allows you to make "Ghost Pins" for varying levels of moisture in the track during the day.