I did find one post that said to try this:
KEY_LEFTPAREN
Of course, that's the only instance of that text on the entire Web.

So this stuff has got to be documented somewhere. Looking at the source, I wonder if KEY_; or KEY_[ will work. Will try, but I don't like guessing (want the official word on what is supported). The above-mentioned post is here:
https://forums.launchbox-app.com/topic/ ... key-codes/
Thanks in advance!
EDIT: I used the configuration command line utility and it turns out the post was right. The other is KEY_SEMICOLON.
EDIT: Aha, removing "Supermodel" from the search query brought up a few more results, including the SDL reference:
https://ocamlsdl.sourceforge.net/doc/html/Sdlkey.html