Execute pfdavadmin.exe on the server,
 extract the files,browse to the extracted 
map and execute pfdavadmin.exe again.

- Click File, connect.
- On the 'Exchange server' and 
'Global Catalog' text boxes, fill
 in your server hostname.
- Select 'All mailboxes' and press OK.

-- ONE BY ONE EDITING OF PERMISSIONS -- 

We can edit the calendar permissions one by one by
- Selecting an user, expanding it, then expand 'Top of Information Store'
- Right-click 'Calendar'
- Choose 'Folder permissions'.

Now you can view and set permissions. 

To set
- Click 'Add'
- Click 'Browse' and search for the user you want to have permissions on this 
calendar
- Select the user and click Ok, Ok..
- Set the permission and click 'Commit changes'

-- ACCESS FOR EVERYONE!! --

Let's say you want everyone to be able to edit and view each others 
calendars.
This is a very common thing in many organizations.

Luckly this tool brings us a bulk permission set tool!

- Click tools
- Click 'Set Calendar Permissions'
- Click 'Add'
- Click 'Browse' and search for the 'Everyone' context
- Select it and click Ok, Ok..
- Set the permissions for everyone.
- Click Ok

A new pop-up reveals itself.
Read it carefully.. in the next dialog you can REMOVE permissions.
The role in the dropdownbox, as the pop-up tells us, has got no effect.
So select the entities you want to be removed by for example the 'Everyone' group.
Right now, we ain't going to use this setting since we are not removing, but setting permissions.
Just click 'Ok' and witness how the tool will edit al the calendar folders..


Reference