The Comcast remotes are not true universal remotes. They are designed to give full control over the cable box, and some basic control over the TV (power, volume, input selection) and/or separate audio system (volume, power).
The old-school remotes can be programmed with a computer and a special cable (note the 6-pin header in the battery compartment.) The remote was made by Universal Electronics (UEI), which make many remotes. The connection is called JP1 and there is software created by users who have reverse-engineered it. Probably not useful for most people.