If I'm mistaken, I'm sure some of the real Comcast guru's will let you know.
I believe Comcast DTAs use a XMP protocol and the component manufacturer's 3 or 4 digit IR codes won't work. I do know that some of URC's learning remotes can learn the XMP protocol. IMHO, a learning remote is a GREAT product that eliminates the need to have and use IR codes.
i used my comcast universal remote to control my converter box i set it up on aux and used the code 01982, i might be 3 years too late but this will help others