Looks like I don't need to waste my time with experiments. The "hack" only works for stations like PBS and other networks, but not the ION/Pax/Qubo channels. I'll summarize incase anyone with Vista Media Center has the same issue:
1. The "hack" is to simply get guide data for a full digital cable band in your area, and assumes the carrier has all the sub-channels *somewhere* in their lineup.
2. This works fine in most areas for PBS stations, and in our area for the KCRA and KXTV weather channels (the .2's).
3. Comcast in our area (and apparently ALL areas) does not carry the digital sub-channels for the ION network (formerly PAX). Found this out from the following posts (the 3rd one down from here describes PAX in particular) http://thegreenbutton.com/forums/per...ad.aspx#196989
4. For this reason, there is no comcast digital channel listings that the manually added sub-channels can map in Vista Media Center.
5. Hack won't work for Qubo, end of story. Oh well, boo hoo.
So, the issue is a byproduct of 1) Vista Media Center's software architectural limitation of only being able to pull guide data for ONE provider at a time. 2) Microsoft does not have a contract to get OTA data from Tribune (Zap2it's parent) because OTA is NOT a true provider. How does Microsoft send out the guide data for the ATSC channels in an area you may ask? Easy: They rely on the FCC rule that the provider must carry the .1 majors somewhere in their lineup, and Media Center just looks for a match on the call letters to map it to the ATSC channel numbers.
Thanks for playing! I'll just enjoy what I have already, and between on-demand, our video library, and her recorded shows, my daughter has PLENTY of crap to watch already.