This is rather bad but working code I use to import meeting requests
into org. I've been wanting to improve it and put it on github, but
haven't gotten around to doing that yet :-/
Just (require '..) both of them, then you should have an additional
button for vCalendar attachments, allowing you to import it.
Replying, Accepting and Rejecting are WIP, parts are there, but they
don't work reliably with Microsoft Outlook yet (which doesn't really
honour the standards at all :-/)

Good luck with it :)

Peter