Without reading all of these posts about the 3rd row seat...let me say that I have the 3rd row seats. My wife and I don't have children yet...but right now the seats are sitting in one of my closets taking up space.
The 4Runner is just too small of a SUV for this type of seating. While it looks and sounds like a good idea, there is just no cargo space once they're in.
Personally, I wouldn't do this mod if it can even be done.