I had the same issue. I think you want to send I/R and have a contact close, not close a contact and have an I/R Command sent, big difference! You can use X-10 and it will work but... A low cost 15 channel I/R kit is available from Jameco. You get a I/R transmitter and a Receiver. You teach the Pronto the I/R codes and then the receiver can be set to "change-over" or "pulse contact" switch each of it's 15 channels. I've done this, it works well to directly switch things with just your remote. I have also used this setup to give direct inputs to my Home Base X-10 controller to initiate larger events like lighting scenes. Giving direct input to the controller where ever possible helps avoid collisions in my very busy X-10 system.
Transmitter P/N 120555 $49.95
Receiver P/N 120547 $44.95
Jameco 800-831-4242 www.jameco.com