Arduino two way comunication over DC

So the reason that I have gotten an Arduino is so that I can build a sensor/control network primarily targeted at sprinkler systems.
The idea is that I can have the following

PSC05 <=> arduino controller <=> station 1 <=> station 2 <=> ......

At the moment I have the PSC05 and controller work, now onto the fun bit.

My thoughts are to use the zero crossing signal as a master clock for all comms and to transpose the tx/rx signal onto the same line. Then use LC coupling onto the DC supply.
I am hoping that this will allow for easy reuse of the X10 Lib that the controller is using.