How should you get the autistic child into the operating room when the mother objects to intramuscular ketamine?

Freddy is a 15-year-old autistic obese teenager who presents for elective circumcision due to phimosis. His mother is present in the preoperative area and is quite concerned about the induction of anesthesia. Her friend, who also has an autistic child, told her that Freddy will have to have an intramuscular injection of medicine in order to "go to sleep" for surgery. Based on prior experiences at the dentist’s office the mother explains that as soon as someone comes near him with a needle he becomes agitated; using a needle for induction of anesthesia would be challenging. When you go to see Freddy he is sitting in a chair with his mother and sister at his side. As you approach him, Freddy gets up and tries to walk out, but his mother tells him to sit down again. He seems to listen to her directions well.