The front part, I keep along side the seat and tuck the shoulder belts under the front of the seat.

 

When in place, you can still use all 5 seats, but the left rear will have a harness next to his face.

 

You could also attach it to one of the lower points of the rear right seat shown here (or both if you use the Rally 4 or similar harness), and some people have used the child seat retention bolt, which is illegal on the street but works fine for autocross.

 

Just fyi, Corbeau makes a nice one just like mine but has an optional retracting shoulder belts. The 4 point models do not have a quick release, so you would have to uninstall the harness every time you want to put it away. And my 3 point shown has a quick release, which allows me to tuck it away when not in use.

 

thanks never seen that, just wanted to see how they hooked up