As an alternative you might consider what I did. Having discovered that my glove box was made of paper I decided to improve it. I made a template of the shape of the bottom using the original, and had a piece of sheet aluminum cut to shape. Instead of the side risers, I used two pieces of 1"x1" angle aluminum to make brackets. I mounted them so that the bottom piece rested on the top of the brackets. Sort of a upside down "L". This made it easier to apply the mounting screws on the two sides as they are now under the shelf bottom. Finished the whole thing in black with a piece of thin rubber for the bottom to keep things from sliding around.
It was a little bit of work, but it ended up being a much better product. If you are a purist this would not work.
Regards
Al /ubbthreads/images/graemlins/canpatriot.GIF