It may depend on how you want to share, but there should be at least two
options:
1. A separate Entourage identity for each person
2. A separate Mac OS X login, with a (separate) default Entourage identity
for each person.
You¹ll probably also have to go beyond that to do what it looks like you
want to do. Theoretically (I haven¹t used it long enough this way to make
sure it works correctly) you can create a project, share it, and have the
other users subscribe to that project. You could have each user publish
their own project, so then it¹s obvious which contacts/events/notes, etc.
are added by which users.