Assign an RDP CERTIFICATE THUMBPRINT to a customized image/VM programmatically

Hey,

My post is somehow related to the following post:

http://social.technet.microsoft.com/Forums/windowsserver/en-US/6dbf451b-22eb-474d-8bca-5c890691aefa/rdp-certificate-thumbprint-not-showing?forum=windowsazuretroubleshooting

I followed the instructions, but I'm using my own image:

$VM1 = New-AzureVMConfig –ImageName $myOSImg –Name $VMName –InstanceSize "Small" –HostCaching "ReadWrite" –DiskLabel "System";

I added a certificate with WinRMCertificate option with Add-AzureProvisioningConfig:

$cert=New-Object System.Security.Cryptography.X509Certificates.X509Certificate2("IPL.pfx")

$VM1 = Add-AzureProvisioningConfig –Windows –VM $VM1 –Password $pwd -WinRMCertificate $cert;
New-AzureVM –VM $VM1 –ServiceName $svcName –Location $location -WaitForBoot

Still there is no RDP CERTIFICATE THUMBPRINT, and the following command gives me NULL:

(Get-AzureVM -ServiceName $cloudServiceName -Name $virtualMachineName | select -ExpandProperty vm).DefaultWinRMCertificateThumbprint

How can we assign an RDP CERTIFICATE THUMBPRINT to a customized image/VM programmatically? Or is there any option at the time ofcapture that could help us to have RDP certificate?

Thanks