It's true the harmony can't talk directly to your RF transceiver, but all you need is an IR-543 box and the harmony will work fine. The only caveat is that you have to be line-of-sight with that box since it's IR. From there, it sends commands via your power lines just like your RF transceiver module. So just make a new device for it. I don't have a dedicated activity set up for mine, but you could if you wanted. I do have X10 commands in several other activities and they work great.