How would Dharma be able to rig a key to make the island move?
They didn't - it was already there. In the one scene where they were drilling and they came up with some x-ray/sonogram picture of the chamber, you could see the wheel in the wall. They were acting very surprised that all that was in there, prompting the fear that additional drilling would release the energy.
My bet is that equipment was placed there by the ancients who "built" the island. I'm still thinking the whole place was a piece of Atlantis or Lemuria or something of the like.