They are technically called threeway switches, you can buy them almost anywhere. There are three connections on the switch one of which is labeled common. The common can be on one side with the other two on the other side or the common can be on the bottom with the others on either side on top. I use a flashlight and magnifying glass to find the word common. When replacing the switch the wire that is on the common has to go on the common, the other two can go on either of the other screws, doesn't matter. How they work? Power into the common of first switch, two other wires to other switch, power out of the common on the second switch to the light.

When all is said and done, four wires are needed: - One neutral wire to feed the lights and to continue from light to light. This is because each light has neutral connectivity whether the lights are on or off. Let's call this the "neutral jumper". - One wire which is hot only when a combination of the switches results in an "on" condition. If it's hot, the lights are on. If it's cold, the lights are off. Period. Let's call this the "switched hot jumper". - Two wires used for alternative paths between the switches which we'll call "travellers". They are complements in that when one is hot, the other is cold and vice-versa. As long as the circuit is in normal operation, they are never both hot or both cold. [Furthermore, one of the two-way switches has to get a "hot feed"--an incoming wire to the circuit that is always willing and able to feed hot power. That comes from the breaker panel or is tapped off of an unswitched portion of a larger circuit. The other two-way switch has to connect to the "switched hot jumper".] Now it doesn't matter whether the travellers happen to run from light to light. That's irrelevant. They can just as well be pulled through the wall studs or under the floor or through the attic. In fact, they often are, depending on layout and distance. Their only job is to provide alternative paths between two switches. But wherever the wires actually run, the bottom line is this: You need four wires: a neutral which jumpers from light to light and is never switched, a switched hot which jumpers from light to light, and two travellers between the switches such that exactly one is hot at any time and exactly one is cold at any time regardless of whether the lights are on or off. Thus, each of these four wires has a state and function that is different from any other wire's state and function. So, no, if I've understood your question correctly, with ordinary wiring materials (no transporter beams or warp wires!), I think you'd need to use magic of some kind.

Sure. Just pigtail your new hot wire off the common terminal of the 3 way switch that powers out to the current light. That's probably the switch at the head of the stair. Pull your new neutral off the neutral in the same box.

Well I got all the wiring done and everything connected, but I must have done something wrong. Everytime I flip one of the 3 way switches it trips the breaker. I think I have wired something wrong in the original outlet. I had a total of 4 different sets of black/white/bare wires coming into that box (I originally said 3). Before I started messing with it, the switch was hooked up as follows: Black wire attached to lower switch screw which went directly up (to the lights or the kitchen outlets), another black wire was attached to the top switch screw (this black wire went from the switch to the pig tale of black screws) the white wires were all just pig taled together (I thought one should go to the switch?). And the grounds were all pig tailed with one going to the ground screw on the light. So the way I have it installed now is as follows: black wires pig tailed together with one wire going to the common screw, black wire from 14-3 wire on one traveler, red wire on other traveler, white wires are all pig tailed (none going to switch). At the new switch I have black wire connected to the common screw and the white and red wires attached to the travelers. I am sure this is very confusing to whomever is reading this. Sorry! JoeD: I tried to follow your advice, but got a little confused, Hopefully you or some can help me! Thanks, Jeff