How will the boxes be affixed? If the boxes you have aren't designed to attach to the metal stud, you may have trouble. If they are the "remodel" type box that clamps to the drywall with 2 plastic tabs, you'd have to drywall first, cut the hole, find the cable(s), insert the box in the hole and secure, then perform the wiring connections. Seems like a hassle to me.
