Distro maintainers can upload distro information directly to Hackage (either manually, using a form, or programmatically using something like curl). It is currently not exposed or documented that well, unfortunately, and it needs a last 10% of work to be fully functional. If you'd like, I think I'd be able to do it this week.
Unlike the previous system, using this *does* require Hackage credentials, and if this data comes from an automatic task, a bot account could possibly be used. It depends on what will work best with the current flow.