Trick I learned from a coworker (Sergeant Rock). Take a regular deep plastic nailon box and remove the nails. Take a saw (sawzall) and cut off the plastic nail holder flanges. Cut the box in next to a stud. Pre drill 2-3 holes in the box on the side that will go next to the stud. Use 2-3 screws to attach to the stud. The beauty of this is you end up with a deep box for your wiring instead of the usually cramped confines of an old work box. Of course it only works in normal situations where you can get next to a stud. Would work beautifully in your situation since the screws could go in the T+G. The smart box is essentially the same principle. Smart boxes don't seem to be readily available from my suppliers. Another must for interior plaster cutting is to use rotary rather than reciprocal cutting. Anyone who has hooked and vibrated a lath board and watched 10" of crack appear knows about this!
