As PFDAVAdmin doesn’t work with Exchange 2010 as it was in Exchange 2007, you might find these Powershell Cmd-Lets useful.
As Here is the list of Cmd-Lets you should use in order to manage this calendar settings:
Here are some examples of use :
Get-MailboxPermission -identity "John Doe"
Add-MailboxFolderPermission -identity "John Doe:\Calendar" -user "Cole Eggs" -AccessRights Reviewer
You should have a look at the help to have more examples:
get-help Get-MailboxFolderPermission - examples
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