daryl
The Power Flash is about the "cleanest" X10 solution if it works a 3V, but you need to experiment. I have Power Flash triggering at 5V input. If you went the reed relay route, you could hack just about any X10 controller and (i.e. the "mini or maxi controller") accomplish the task.
There are also non X10, RF controllers that turn on a special light switch or module. They are usually marketed as a cheap way to add three way control.