I doubt that you'd need a FEW grams. One gram or less would most likely kill anyone without a tolerance. Just bang a ton of horse into your ballsatchel after consuming about 20 mg or more of Xanax
I'd use or add a more sedating benzo, like diazepam or something along those kind of lines. Based on previous experience mixing difference benzos with alcohol on humans, at least. Xanax = violence, amnesia, aggression, then loss of balance and hypnosis. Valium just knocks them out.