A four way has four screws, usually labelled in pairs as "in" and "out".
For sake of explanation, we'll call the four screws a name, "in-left and "in-right", and "out-right" and "out-left", going clockwise... (follow me so far?)
Think of the internal connections between "in-left and "out-left",and "in-right" and "out-right" as an =, and the connections between "in-left" and "out-right", and "in-right" and "out-left" as an "x".
The travellers will either connect to one side or the other on the "out" side as the toggle is thrown.
As far as wiring, put the hot travellers on the "in" side and the load travellers on the "out" side, you may keep the black to black and red to red (or any other color other than white, green, natural grey, or green with a yellow tracer) for courtesy's sake, but they'll work fine reversed.
Don't be confused with the screw colors, black screw to black wire, silver screw to white wire would be incorrect and the device won't do its job this way.
Internally, I've never dissected one, but I imagine it to be relatively simple mechanically.
[This message has been edited by sparky66wv (edited 11-24-2001).]
