Enlarge the holes in the cut-in box so that you can easily slide in roofing nails.
Remove the mounting screws from the receptacle and slide it in the cut-in box.
Slide the washers over the roofing nails, and put the roofing nails into the cut-in box.
Attach the faceplate with a screwdriver. The faceplate should slide easily in and out of the cut-in box.
Place the open end of the cut-in box on the wall and use the pencil to trace around it.
Cut a hole in the wall with a drywall saw.
Place the cut-in box in the hole and tighten the screws. Hide your small treasures in the box and replace the faceplate.