Sharing Calendars in Entourage

(untested) this is copy and paste

First, make sure that the public folders are assigned correctly. (ver 11.3.4 or later)

Open Entourage, click on your calendar.  Once in calendar view you will see a list of calendars (usually Calendar on my Computer and Calendar ASD Exchange or something that reflects the calendar attached to your ASD).  If you right click (Ctrl + Click) on the ASD calendar you should get a list and choose 'sharing'.  Type in the username of the person with whom you want to share and click 'find'.  You can check which privileges/permissions you would like that person to have.