Change published FQDN for Server 2008 or 2008 R2 RDS Deployment

I came across cmdlet that allows to change published FQDN for Server 2012 or 2012 R2 RDS Deployment and it works great. But it doesn't work for 2008 and 2008 R2 servers. Does anybody know how to fix existing cmdlet so it works for 2008 and 2008 R2 servers?

cmdlet for 2012 and 2012 R2 servers is here: https://gallery.technet.microsoft.com/Change-published-FQDN-for-2a029b80

Whe I run it on Windows 2008 R2 I get an error:

Invoke-WmiMethod : Invalid namespace
At C:\Scripts\Set-RDPublishedName.ps1:21 char:16
+     $ret = iwmi <<<<  -Class "Win32_RDMSDeploymentSettings" -Namespace "root\CIMV2\rdms" -Name "GetStringProperty" `
    + CategoryInfo          : InvalidOperation: (:) [Invoke-WmiMethod], ManagementException
    + FullyQualifiedErrorId : InvokeWMIManagementException,Microsoft.PowerShell.Commands.InvokeWmiMethod