jbworks:you will need to rerun tv setup and select "have a set top box" This will require you to have IR Emitter attached to the IR receiver that is used by MCE. I haven't tested it, however I believe there are some issues getting the standard MCE remote to record the IR codes from the Comcast remote.
Your other option(a no brainer for me) is to replace your analog tuner with a QAM tuner. You will be hard pressed to find a better tuner then the HDHomerun.
Unfortunaly, if he has a digital package that includes ecrypted channels, HDHomerun won't help there. Then you are back to haveing a IR blaster or swticht to a cable card tuner.
Prices on Cable Car tuners on ebay have fallen to the point where I would pick that over the HDHomerun. Cable cards run about $2 a month from the cable company, and you get all the channels you would get with the box (less the on-demand content).