Try a paper sack over top of the crayon and a warm iron. Iron over the sack, moving it to clean areas as the wax melts onto the paper. Once it's just the ink, work on the stain. I used this method for a candle and it worked perfectly (royal blue candle, beige carpet). I then steam cleaned the carpet. Should work well.

If it doesn't call a carpet cleaning company, they may have an idea.

The crayola website has crayon removal instructions.