...doesn't work in HTML exports.

(oops) stated as such for v0.1.11:
"Mousewheel when devkit mouse enabled: stat(36) // not supported in web"

not sure if "not yet" or "not ever" though.

Ought to be possible. I've seen custom scrollable regions in HTML before, so clearly it's possible to intercept the scroll event before it goes to the document's default handler.