Find and mark the vertical studs behind the plaster, using a stud finder and pencil. Make three to four pencil marks vertically over two studs on the plaster.
Select a drill bit that is equal to or slightly smaller in diameter than the cabinet mounting screws you are using.
Attach the bit to a drill and tighten the chuck. Drill holes through the pencil marks on the plaster wall.
Ask an assistant to hold the cabinet in position, aligning the holes in the back of the cabinet with the pilot holes you drilled into the plaster, lath and studs.
Drive screws through the holes using a screw gun to fasten the cabinet against the wall. Allow the cabinet to hang freely to ensure it does not sag or pull away from the wall.