If you and the other users using Entourage 2004, you can use the new Archive
feature to do this easily. First, go to Edit > Categories > Edit
Categories, and create a new category with a name like "Events to Export".
Now, create all of the events in the calendar, and make sure they all have
the category "Events to Export" by going to Edit > Categories > Events to
Export when you're creating them.
To export the events, go to File > Export, and choose to "Export items to an
Entourage archive: items that are in the category Events to Export". Check
"Calendar Events" in the section below, and then continue.
Once you've saved the file as an RGE, create a new message, address it to
all the employees, and attach the RGE. Send these directions:
To import the attached Entourage Archive (.rge file) and included calendar
events, select it, and click the "Save" button. Save it to the hard drive.
Then, go to File > Import, and choose to "Import information from an
Entourage archive". Select the archive you just saved, and then import.
The events should then appear in your calendar.