If he's on the controls and actually flying and won't go around, I'd be keying up the mic and telling the controller we're going around. Whether the captain continues or not at this point is up to him, and the chances of getting hurt when he ducked below minimums while you have a perfectly normal runway in front of you are slim. In any event I'd call off the trip as soon as we were on the ground safely. I've got no interest in flying with clowns like that.
Now, that being said, I've never flown with a clown like that. I think the more likely situation is that the skipper keeled over and nobody is flying the airplane. If that's the case, then I'll take the plane and go around.
Pretty straight forward, but the most important thing that people have been saying here is that YOU DO NOT WANT TO WRESTLE FOR THE CONTROLS!