ADMGS aka AD Web Services aka Powershell Native AD cmdlets which is originally a Windows Server 2008 R2 feature is out of beta and can be downloaded from here for DCs running down level OSs.

The Active Directory Management Gateway Service enables administrators to use the Active Directory module for Windows PowerShell and the Active Directory Administrative Center running on Windows Server 2008 R2 or Windows 7 to access or manage directory service instances that are running on Windows Server 2008 or Windows Server 2003 DCs.

“Note:    Installing the Active Directory Management Gateway Service on your Windows Server 2008–based or Windows Server 2003–based servers does not make it possible for you to install the Active Directory module or the Active Directory Administrative Center (which is available only on Windows Server 2008 R2 or Windows 7 operating systems) on these servers. “

For more info see http://www.shariqsheikh.com/blog/index.php/200907/what-is-active-directory-management-gateway-service-admgs/