So the saga continues into the early morning...
Everything compiled rather easily, but to get the plugins to all work the way I wanted I had to add the following packages using apt-get:
Some of this would likely have been installed had I used 'apt-get build-dep mythtv-plugins' but I didn't think that far ahead.
I also had to download and compile taglib.
MythTV wouldn't start the setup process until I added libqt3-mt-sql.
After that, I was able to setup my zap2it subscription inside MythTV (see the MythTV HOWTO for details) so it will download the TV listings for me.