Adding Metadata to vDC

I have an application that creates a vDC and then create a series of vApp's within the new vDC. I need to store some information (key value pairs) for future reference.

I see how to get the meta data from an existing vDC. But I don't see how to set the meta data for either an AdminVDC or a vDC.

Any help would be appreciated.

Thanks.