In 2006, the only way to make that mate is make a rack that is essentially a gear of almost infinite diameter and od a gear mate. In animator, you can fake the mate by having your rack and pinion move through their respective distance and angle mates at the same time. If you really want convincing mating of the two, it'll take quite a bit of work. If your pinion is going to rotate more than 360 degrees, you will need to break it up since swx can't rotate past 360. I recommend rotating from 0-359.9, then do a rotation from 359.9 to 0 in an tiny segment of time, then repeat.