You should be able to disconnect and connect VMDK files through the vmkfstool in the VMA, and perhaps you could in some way script this adding and removing.
However, could you be sure that all files are closed and saved properly from inside the VM before hot (hard) removing it?
If possible, the plan will be to qiuesce the filesystem, eject it frorm the OS, then have vMA unmount and move it to the new box. We'll do this with a script executed by the user that does the Windows side quiesce/eject, then call a CGI script on the vMA server to flip the VMDK over to the proper desktop. In the end state, this will look like a 4GB thumb drive to the user (only SCSI instead of USB). That's the theory anyway. Thanks for the vmkfs-tool tip. I'll play with it.
Maybe possible using Vcenter Orchestrator to script the full workflow (sorry just started reading the VMPress Vcenter Orchestrator book) ?
Also, could I ask why you can't do it over the network as wouldn't adding the VMDK of the control VM to a normal VM just negate that security (of course unless its a seperate VMDK with the items on that are not such a security risk)