The best way to apply Prozap Mole Bait is to make a hole in the top of the tunnel near the ends of the tunnel. This hole should be about the size of a broomstick and penetrate the top of the tunnel, but not collapse it. The Prozap Bait is then placed inside the tunnel through this hole. It is best to put a small rock, stone or brick over the hole and not fill it with dirt. The dirt will cover the bait and this is what you are trying to avoid.
As far as the Yard Butler, if you can find a way to place the bait inside the tunnel using it, then it should work.