Just as lburou said, go in through the underside of the dash. Just pull the pannel facing the floor, the one with the liggh white globe in it that houses the floor light bulb.
Only other note I had was pay attention to the couple of inch plastic "pin" on top of the ECM carrier. It inserts into a gromet up in the dash. It will go in without hitting the hole but it will have no upper support thus has a little wiggle room.
Brent