Such a community is probably the hardest to find moderators for. You need moderators who are willing to go toe to toe with users that are going to get in their face, but that have the restraint to avoid inflaming the situation while carefully measuring the appropriate amount of pressure to apply to maintain respect and control. They also need to have the skill of being able to evaluate if their position really is what the community needs and be able to change their position without it appearing that they were backing down from being pushed.
These aren't characteristics that frequently go together, so it can be pretty hard to find someone who has them all. The one thing that works in your favor is that such a community does tend to attract people with that personality type though, you just need to know what to look for.
Look for someone who is level headed and, while willing to go forcefully toe to toe in a heated debate (without becoming condescending), is also graceful in adjusting their position as they go. In general, it will seem like their debates tend to have better results and while you won't be able to put your finger on when their position changed, it will be clear that over the course of the conversation it did move (though not necessarily all the way to the other person's view). Conveniently, such users will also typically already command the respect of the community, even amongst those who frequently disagree with them.
If a user tends to be completely stationary in their opinions, they are too stubborn to deal well with moderating such a community. If they tend to waver too fast, they are unlikely to be able to stand up to the pressure they will be under as a moderator (though in some cases, they get more of a backbone when they become a moderator, but this can sometimes go too far to the other extreme too.)