I'm not sure if there's an actual guide out there, but it's actually not that different from migrating a VM Pro from a computer to a virtual computer or vise versa. The main thing you'll need is a file transferring software. I like using WinSCP. This will allow you to transfer the primary folders, which are Accounts, Names, Greeting, and Wavs out of the UC module. For the Wavs folder, only transfer the wave files, not the system or custom folders. Then use the VM Pro client to export the Call Flow menu trees and then import them into the new voicemail computer and in the same locations.
BTS Tech