Lyndel,

There is NO IR Input or External IR jack on the back of this unit. I believe it's the Arris XG1 unit that I have, though there is no name on it.

You said that "You somehow have to find out what IR codes they are using." My thought was that I could take the Comcast remote that emits RF codes and aim it at what I am calling "Unit 2" and that Unit 2 would do the translation and emit an IR code that the ProntoPro would learn.

Are you saying that that approach cannot work?

Len