[JLV]

Personally, I'd say it would almost have to involve some kind of magical means (a special pentagram, or some kind of magical "blanket" that prevents him from touching his magical power somehow -- which raises all sorts of collateral questions on just how a Wizard does that...), unless you can place him in a cold iron box or cage sufficient to prevent him from doing anything. Unfortunately there aren't any real guidelines on how cold iron would work for something like that.