Unless a starter box is made specifically for a car, there is no set way to set it up.
The first thing to do is put the car on the box so that the flywheel is exactly over the peak of the rubber spinning wheel - ensure that the flywheel as close to parallel with the rubber wheel as possible. Then you can try and trace out teh shape of the chassis onto the starter box. You can use that outline to figure out where to put the pegs. Usually having two pegs at the front, and two at teh back works well. I don't know the R40 chassis, so I can't say specifically where to put the pegs.
Hope that helps,