If you are lucky enough to have an AC receptacle below the "low volt" version you could fish/drop a wire down to it and plug in a "x10 powerflash module" and screw the wires onto it. Set the slider switch on it for "contact closure"

[Link: smarthome.com]

not fun to look at in a family room though (that's why I said dangle a dongle, meaning hidden inside the wall).