I tapped into some older threads on this question, so I thought it best to ask again because the documentation for the PR 180 seemed to have some ambiguities.

I have a stair case with one light at the landing controlled by two switches, one at the bottom of staircase and the other at the top. I intend to replace the top-of-stairs switch with the PR180 so I opened the existing switch box to check its wiring. When I turn the switch face down and look at the backside of it, there are places for two wires at the top, a red one on the left and a black on the right. On the bottom left there's a place for only one wire and it is black also. I was hoping I could just plug the wires from the existing switch into the PR180 in their same relative positions. After reading the thread comments, that expectation seems too good to be true. I'd welcome knowing if my approach would work as described; if not, is there a relatively simple description?

If the travellers are not the same color, First thing, at each switch is to Identify the Common, the wire on the dark screw(on both switches).
This can save you a lot of time.
I don't have the immediate solution, have been many post this, and could be found by searching on this site.
Good Luck.

I think what Strat is saying is to look at the old switch and see which wire is connect to the common terminal (it will be marked). Connect that wire to the common terminal of the new switch. It doesn't matter which terminal the other two wires are connected to.