Michael, A few things to know, and depending on what part of the country you live in it might go something like this. You said you only have 2 wires right. Most likely 1 black and 1 white. Most likely they brought the hot lead into the light box and not the switch box. This means they pulled one wire into the box that has 2 conductors in it. Most likely the hot side is the black going into the switch and white would be the return side back up to the light. You find this type of wirring on garbage dispolsols alot.
The other way is they would bring 2 wires into the switch box(each having a black and white in it). 1 that has voltage on it and the other a return feed up to the lights. In this case you might see that the white or common wire are wire nutted together and pushed out of the way and 2 black wires going into the switch. This way is the most common way to see it.
Either way if the old switch has worked for awhile and you swap in the PCS switch you should really not have a problem. Just go slow and pay attention and mark the wires if need be. Also kill the breaker switch to cut power from that circut. Some electronic devices do not like to be wired hot.
