So I emailed Tesla support requesting the option to warm the battery, stationary in my garage, using whatever they use to precondition the battery while nav'ing to a super charger. After about a week they just sent me this email:
Thank you for contacting Tesla. I apologize for the delayed response, but I am happy to assist. Improve efficiency and performance in cold weather by preconditioning your car before you drive. Just tap “Climate” in the Tesla app and set your desired interior temperature. Your cabin will maintain that temperature as long as your battery is above 20%. The following features will automatically turn on for your convenience:
In cool temperatures -
• Front seat heaters and any equipped cold weather features
• Front and rear defrosters
In near-freezing temperatures -
• Battery heating, which improves the following functions:
1. Stronger regenerative braking
2. Faster charge times
3. More powerful acceleration
When you return to the car, your climate settings will revert to your last driving preferences and your battery will continue to warm up as you drive.
You can precondition your Tesla anytime, anywhere—even in garages and other closed spaces. Here are a few best practices for improving your car’s performance in cold weather:
• Precondition your car for approximately one hour to heat your battery before you plan to drive, especially in near freezing temperatures
• Charge your car while preconditioning to reduce the amount of energy loss from your battery pack
• Turn off Range Mode to avoid limiting the power available to precondition your car—even when charging
Setting a higher cabin temperature on the mobile app will not precondition your battery faster. Also, enabling “Max Battery Power” in performance cars will not precondition the car any faster, but will increase the maximum temperature your battery will operate at.
Let me know if you have any further questions with preconditioning.
Just thought I'd post if anyone was interested.