It has never happened-directly. But the Constitiution does not require a justice to be a lawyer. In fact, many Presidents nominated politicians (former lawyers) holding elected office rather than judges since they were more "in-tune" with the wishes of the public. These politicians were lawyers at one time or another, but they were chosen for their non-active legal status.
Once again, I don't think it a) COULD happen or b) SHOULD happen.
I'd like to have people up there that know what the hell they are doing. I wouldn't have a non-doctor operate on me on the theory that they can always read a book, and I wouldn't want a non-lawyer Supreme Court justice for the same reason.
But as I mentioned earlier, the Supreme Court has held in the past that a criminal defendant has a right to an appeal before a legally trained judge, so I don't think this would fly, although query who would have standing to challenge this.