Pry the molding from the wall with a crowbar if the molding is already installed. Set the molding below the space it was removed from; it makes reinstalling easier.
Load the stapler per manufacturer's instructions.
Punch a small hole at the top of the wall and another below it where you plan to place your electronics. Run cable through the lower hole, up through the higher hole.
Hold the cable against the wall -- about 1 1/4 inch from the ceiling -- with one hand while holding the stapler in the other.
Place the grooved guide in the bottom of the stapler over the wire. Squeeze the handle to dispense a staple. Continue running the cable along the wall and stapling it every 12 inches or so.
Attach the crown molding by nailing it into place with a hammer.