..in my old house, the walls are all plaster (in some cases drywall over the plaster too). Here is my method for putting in the boxes. It works well and the are certainly solid. First, I mark out the box on the wall by turning the box around and using a pencil, pen, whatever. Then I use a brand new razor blade in my razor knife and score the rectangle using a straight edge. A few passes and the plaster can be removed with clean edges. Now you see the exposed lathe. I take a hacksaw blade and fit it between the lathe and cut straight up (or down depending on the alignment of the lathe) up to 1/4" from the edge. I move to the other side of the lathe and do the same. By not cutting through all the way on the first cut, it keeps the lathe from vibrating back and forth and unkeying from the plaster. Once the lathe is gone, I feed the new sheathed electrical cable through, and clamp it into the box after exposing the neutral, ground, and hot wires. Insert the box into the hole, drill pilot holes through the plaster and into the lathe using the tabs on the top and bottom of the box as a guide, and secure using wood screws. I don't bother with the wings after my first couple of tries with plaster walls. I found that an odd piece of lath here and there kept them from lying flat.