You point the configuration to subdomain.domain.com. You can setup the VI3 Management that is a member of subdomain.domain.com, and then when you login to the VI console you can utilize your subdomain.domain.com accounts to access and give permissions to the console.
We have the same setup. Our main is domain.com. We have several locations around the world, as location.domain.com, so it's the same we you would setup, and we don't have any problem.
