They use the Iowa Acceleration Scale, but just leave out IQ scores and adjust the total possible points downward to remove the available points for IQ. They also allow parents to fill out all of the subjective parts -- how they get along with peers, how quickly they finish assignments, etc. -- which gives the parent a lot of room a give the kid high scores that will sway the overall #. We insisted on having dd's teacher fill everything out that was at all subjective. If the kid doesn't come out as a good or excellent candidate on the IAS, the school recommends that they not skip, but ultimately the parent can override that decision.
