[CalendarServer-users] Calendar Access Control

I'm trying to set up a calendar server with group calendars to which most people will have read only access, and a few key people will have write access as well. Is there currently a way to set up a permission scheme like this? From my research, I read that ACL support is implemented in the server, but that no clients exist to take advantage of this. Is this still the case? If so, is there a way to manually change ACLs from the server? Thanks. Darren