I'm facing very similar issue (see http://communities.vmware.com/thread/437212) and am exploring so many directions without much success.
One of the directions I'm looking at is setting up a "vCloud Connection" between my private vSphere and the vCloud - this should allow me to move VMs between the two. So in theory, I should be able to set these parameters in my vSphere and then move the VM to the vCloud.
However, even if this will work, this is far to complex to solve my problem 