I'm trying to get a -current i386 kernel up and running (to see if it
   fixes my previous X11 hangs), but the new config seems to have some
   problems. The lex lang.l's definition of ID is incorrect - at
   least, it won't parse most of the numbers in the config files. And
   even with a fix for that, I'm getting errors accepting `at'-style
   config syntax.

You should be using config.new(8), not config(8).