Hi, I'm just guessing, but you might have troubles accessing other peoples Outlook processes
because of access restrictions (other user and/or other computer) - which is annoying but good.
Outlook uses normal eMails to invite to appointments.
Maybe sending invitations to the people in question is an alternative unless there
is a requirement for a silent calendar update? However, depending on the number of
invitations it could be annoying to receive 20 or so invitations at once.
This link might be a starter:
Exchange Compatible iCAL Invitations
Another option might be to create and share a calendar specially provided for event-announcements
(e.g. Share your calendar information)...
Directly accessing the Exchange server would probably be the cleanest solution, but that's beyond
Maybe another Monk knows....?