I keep our hot water lines hot throughout the day so we have instant hot water at every tap. Of course, if you are willing to wait a minute to purge the lines, you can just turn on the pump as needed.
Our small hot water recirculation pump (Grundfos) runs fine on a lamp module. I switch it on for 70 seconds every 15 minutes during the day. 70 seconds was long enough to refresh the water in both loops. Be sure your pipes are very well insulated to minimize the thermal loss.
In your case you need a X10 transmitter at every location. For example set the pump on H1. Trigger H1 ON to turn on the pump. If you have something like a CM15A, have that H1 ON also trigger a 5 minute delay macro that issues a H1 OFF at the end of 5 minutes.
That H1 ON could also be issued by a motion sensor near each location where hot water is used. In that case, the H1 OFF could also be issued by the motion sensor.
Something to consider with the “on demand” approach is that unless your loop actually includes the feed line to each faucet in the loop, the last several feet will not be refreshed. However, by keeping the entire loop hot, the feed lines to each faucet are also kept warm by gravity feed (assuming the hot water loop is below the faucet). So there is hot water available virtually the instant the faucet is turned on.
Oh - if you do this with a lamp module, be sure it is one of the early ones without ramp-on / ramp-off.
Jeff
