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 my experience.
Maybe another Monk knows....?