You must be speaking of Powerline networking.
Using the house wiring to carry the networking signal.
Powerline networking should work for you.
PoE as I know it, is supplying the electricity a device needs
through the Ethernet cable.
We sometimes do this to power video surveillance cameras.
There are network switches available that supply the power.
Check out the Powerline networking components at Newegg.
Example > http://www.newegg.com/Product/Product.aspx?Item=N82E16833122097
Read the customer reviews of these products. Some mention electrical interference.