Crucifixion would have been a lot more painful if it had been done with a single nail to the head. I know what you're thinking, but Dark, the point of crucifixion is slow, painful death, not instantaneous death. Well, <cliche>blah blah blah Phineas Gage survived something similar</cliche>. And I know enough about neurology to selectively paralyze the arms and possibly the legs so that they could not struggle free. Struggle, sure. That'd only make it more painful.
At least, I think I know enough. I'd probably get the hang of it after a few tries. I'm a quick learner.