^ That method sounds way better than what was done in my XJ. When I bought it, it already had 2 child seat tether bolts installed. Both were installed by apparently drilling a hole through the floor in the trunk area, inserting the bolt through the floor, and installing a huge washer (like 2 or 3" diameter) before putting a nut on the bolt. It's secure, but the tether gets in the way when you are trying to carry large items in the trunk.
I'm going to look into the method described above to see if I can find the pre-tapped holes on mine. I always thought the method used in my XJ was weird compared to other vehicles I've seen.