How do you schedule "Mobile" service for Model S
You don't schedule mobile service directly. You schedule service through the app or the service center. If the type of work you need lends itself to mobile service and a mobile technician is available in your area, they will call you and offer mobile service to you. It works great when everything lines up nicely.
I know someone who can schedule mobile service straight from the app. The rest of us need to wait to hear from Tesla.