I did this a couple months ago. Its great having power seats now.
The stock connector that goes under the seat is missing the pins that supply power to the power seat motor/control. I just ran 12V and GND to the seat with 2 new wires.
I stole the power from the wires that run to the power window/locks in the door. It needs to be live all the time so that you don't have to put the key in to move the seat to get in.