I finally got past the block that's been sticking for more than a month (the inability to get a multilib version of both glibc and gcc), and was happily rolling through the automated update script when I hit one of the expected snags. No big deal, obviously others have hit it, and there's detailed instructions on how to fix the problem.

But they didn't quite work. Somehow the emul-* packages got masked and when I unmask them they refuse to install. Sigh. No 32-bit apps for a while I guess.