This is in the context of the international keyboard feature, which places
an icon in the notification area, and you can select between keyboards for
multiple languages, and each language can have more than one keyboard
layout.

I've been poking around in the WDK, but I haven't found anything that gives
me a clue as to how to add a new keyboard layout to this arrangement.

Does anybody know where there's some helpful information on the Internet?

Thanks,
Jeff