That’s more information than I understood before… . . Something like this in plugin.rb:
add_to_serializer(:category, :your_plugin) do
some_stuff
end
I think what you want to do, though, is look for some other plugins that are likely to add stuff to the serializer. I think that Topic Ratings Plugin or Topic List Previews should be good ones to look at, and hopefully it’ll be “obvious” (but only after you’ve spent hours doing a bunch of other “obvious” things, if you’re llike me).