As long as you can keep him alive while you're pulling his spine out, I don't see why you couldn't make that excruciating. Or maybe just break the vertebrae one at a time? I've heard nerve pain's the worst kind of pain there is.

I mean, in reality, I'd probably just stay far enough away so he couldn't get a foothold in my brain and shoot him in the eyes. Threat neutralized. No sense giving him time to defend himself.