I have 3 light switches that all control the same 2 lights, upstairs and downstairs hall lights.  I believe this is called a 4-way switch?  I've looked around and have only seen a 3 way X10 switch.  Does anyone know of any X10 compatible 4-way switches out there? Or have any suggestions how I can get these lights controlled by Misterhouse, other than re-running the circuits and switches?
 
Thanks,
Jeff