After a couple fits and starts, I have HDHomeRun nearly working.
Background in case someone else runs into any of this (or just skip down to the questions):
The first time I plugged my HDHR in I received the LMCE pop-up asking to add it. I said yes and it seemed to go on it's merry way. I gave it a good hour or two, then did a full reboot, still unable to switch Inputs to the HDHomeRun. A quick check in lmce web admin showed it was there and looked ok, but running mythtv-setup from command line showed no HDHomeRun entries. I removed the device from the web admin, unplugged then plugged it back in, and again was prompted to add it. This time it took me to the setup wizard so I knew it was acting different than last. After working through the setup wizard and giving it time to scan channels, still no love. Back to mythtv-setup where the HDHR tuners showed up, and the starting channel was set to something like please add a valid channel. Channel scan - nothing. At this point I rebooted my desktop (not the core) to windows simply because I had an install disk and I figured it would have more tools. After a couple firmware updates (maybe this was the key?) I was able to see channels in Windows, so back to linux for ssh w/X to run mythtv-setup again. This time I was able to scan channels.
Question 1: how should I scan the channels (assuming cable)?
A bit of googling implied I should set it to cable (obvious), then scan both QAM256 and QAM64. I take it this mean scanning will find and add any additional channels no matter what type. Is there any harm or benefit to scanning all 4 ways (QAM64/QAM128/QAM256/8-vsb) as long as existing channel treatment is set to minimal update?
Question 2: I'm clueless on how to map the Digital channels to the Schedules Direct/Comast guide, how is it done?
Unfortunately it appears EPG data is poorly supported (by Comcast, not Myth), so I feel I need to stick with Schedules Direct.
One oddity I noticed. My QAM capable TVs will scan and find channel 2 and 2-1. I look for this as a kind of test case because I know 2-1 the DTV version of cable channel 2 and analog channel 2. I was concerned because in windows I scanned a few times and it never found 2-1. However, MythTV seems to have found 2-1.