Take the Disney Bus to Magic Kingdom.
Then get on the Monorail to TTC.
Walk to the Dog Kennel from the Monorail Station (Out to the Left).
Take Richard Petty Van Shuttle from TTC Kennel to the Race Track.
Back in the mid 90's, we went to the IRL race at WDW. We just walked from the TTC to the track, Poly isn't that much farther, so walking could be an option.