You need to talk to your Doctor.
Get him to refer you to an Occupational Therapist with the following request.
Please evaluate and treat to provide with adaptive equipment in order to drive a Standard Transmission car.
Here's a template.
To whom it may concern:
Mr Dge Viper1 is an X year old man who is one week status post surgical repair of a torn Ulnar collateral ligament of his right first metacarpal phalangeal joint. He will need to be immobilized in a cast for 3 months. In order for him to be independent in daily activities it is medically necessary that he be evaluated by an Occupational Therapist to be provided with adaptive equipment so he can operate a standard transmission vehicle.
Without such adaptive equipment he is at risk for reinjuring his surgical repair and may require a second procedure.
Sincerely,
Dr Beau N Doctor, M.D.
Maybe that will work.