I have a user that is interested in the Interent Calendar feature. The user
guide gives the following instructions:

1. In the Folder List, right-click the main GroupWise calendar, then
click Subscribe.
2. In the Location field, type the URL of the Internet calendar you
are subscribing to.
3. In the Folder Name field, type the folder name for the new
Internet calendar.
4. In the Update Frequency drop-down list, select how often you want
the calendar contents to be updated.
5. Click Subscribe.

Where / how can I enable this feature?