How do I get an alphabetized list of U Verse channels?

Actually the generic link for att's channel lineup is

https://www.att.com/channellineup/tv/tvchannellineup.html?tvType=iptv

and you can get a pdf of the info from that att's site as well.  But even that won't give an alphabetical listing. 

IMO an alphabetical list is a waste of time.  You are going to have to go through the hide channels setting anyway to hide all the channels that aren't in your package.  If you don't you will have to scroll through hundreds of channels in the Guide or when you go to the next or previous channels.  And out of all the channels you do get you can get you should also program the Favorites for the much smaller set of channels you actually want to view because in each tier there's many crap channels I think nobody in their right mind ever wants to see but att is forced to carry in order to carry some other channels people do want.

Programming the guide and favorites shows you the channel number of the station name so you can see "who's on first".