Set-ACL Permissions
Set File permisions on a directory
http://chrisfederico.wordpress.com/2008/02/01/setting-acl-on-a-file-or-directory-in-powershell/
http://technet.microsoft.com/en-us/library/ff730951.aspx
$acl = Get-Acl c:\temp
$permission = "BuiltIn\Administrators","FullControl","Allow"
$accessRule = New-Object System.Security.AccessControl.FileSystemAccessRule $permission
$acl.SetAccessRule($accessRule)
$acl | Set-Acl c:\temp
$colRights = [System.Security.AccessControl.FileSystemRights]"FullControl"
$InheritanceFlag = [System.Security.AccessControl.InheritanceFlags]"ContainerInherit,ObjectInherit"
$PropagationFlag = [System.Security.AccessControl.PropagationFlags]"None"
$objType =[System.Security.AccessControl.AccessControlType]::Allow
$objGroup = New-Object System.Security.Principal.NTAccount("BuiltIn\Administrators")
$objACE = New-Object System.Security.AccessControl.FileSystemAccessRule `
($objGroup, $colRights, $InheritanceFlag, $PropagationFlag, $objType)
$objACL = Get-ACL "c:\temp"
$objACL.AddAccessRule($objACE)
Set-ACL "c:\temp" $objACL