Hi,
I am not quite sure this will be a best practice but in my opinion, this approach could be achieved.
One thing is, during the installation of the Update Manager, you need point to a vCenter server. Probably you have a standalone ESXi 5.x box which isn't registered/managed to/by one of the vCenter servers?
Please keep me updated how it goes, this is quite interesting Image may be NSFW.
Clik here to view.
Regards,
Steven.
