I believe we have shared groups working through group properties at the moment. Check out the getPropery/setProperty methods. You should be able to figure out the syntax quite easily by looking at the values set by the admin console.
Thanks Matt, I had an idea it might be to do with the properties but the Group object only has getProperties(). Am I overlooking an object with setProperties()?
… but it is broken and it’‘s not working :-(. I mean - it is working after a server resart, e.g. it serves for nothing if you’'re using a custom auth/user/group provider.