I have a switch that controls a light. The owner has asked me to add another switch. This will allow the light to be turned on at either location. Obviously, this is wired as a single-pole and there isn't a 3-wire involved. The second switch he wants me to cut in is right next to an outlet. I know I can get power to the switch from the outlet. What X-10 devices do I need to purchase for at the switches and at the light fixture?

Thanks for your help.

Byron