Scott,

You could use a Split Receptacle Module but as it requires wiring in I would not recommend that route, certainly to start with. Rather, you should get an Appliance Module which requires no wiring in. At the SmartHome website, the Appliance Module is item# 2001 ([Link: smarthome.com]) or 2002 ([Link: smarthome.com]) depending on whether you want it grounded or not.

As I don't have an MX-980, I don't know how you would program it. The IR543 accepts standard X10 IR codes and on my Pronto such codes are part of its factory database.

Yes, you can add more Appliance Modules (or Lamp Modules) and control these via the IR543. You do this by setting each module to a different code using the dials on the front. However, X10 is not that reliable and whilst I find it good to control a few devices I got a bit frustrated when I tried to move all the devices in my home onto X10. There are other standards which are generally thought to be more reliable, such as Insteon, but as far as I am aware they don't have convertors like the IR543. Also, they don't work in the country that I live in (Australia).

Finally, note that the IR543 sends X10 signals via your electricity cables not RF signals via the ether. No RF is involved.

Guy