This was pretty messy work, but not too bad for my first try. This is an exterior wall so there wasn’t a lot of depth to work with; about 2" between the back of the lathe and the face of brick. I was able to cut a hole out with the Rotozip, although it took me 20 minutes to go through 1/2" of plaster + 3/8" of 68 year old lathe strips (it’s pretty dry, tough wood at this point).
I had just enough space to snake the cables between the edge of the sub-floor and the face of the brick, although I did have to bust out a couple of blocking bricks (between joists) with a small sledge hammer. I had to pay close attention to come between the joists and studs, which are not necessarily aligned.
Finally, I sealed off the edges around the outlet mount with "Good Stuff" expanding foam and then tacked the wiring to the joist below. The cable ends all snapped right into place and the cable terminations were easy to do with a good 110 block tool (don’t waste your time with the plastic tool/junk they include in the package, in my opinion).
