Be Careful
The cambered bar can make your bench very strong, or destroy your shoulders. It did both for me.
I used 2x6 boards and 1" oak boards to vary the depth. The full camber is too great of an increase in stroke. It will put alot of stress on your shoulders. Start off with enough boards on your chest so that you are only going an 1" lower than normal. Gradually you can take boards away, but I don't think there is any point increasing your range of motion for than 2" below normal because the chance of injury greatly increases, especially for a big fat guy like me. Smaller lifters aren't usually as tight and can do a greater range of motion.
If used in conjuction with jump stretch bands, you can strengthen your bench dramatically. Used double looped mini's if you bench 300-400, monster mini's 400-500, above 500 use the light band. Sets of 3 reps on max effort day are used but you have to stay tight. If your form breaks down your shoulders are going to get wacked.
You can also flip the camber around and do partial benches. The camber is great for doing shrugs because the bar won't hang up on the legs. It can be used for tri ext around the head area to increase range of motion. Another good one is to put an incline bench in the power rack, and lay on the bench to do rows. The camber will go around the bench so that you have a chest supported row.
Be careful. I don't bench anymore because I hurt my right shoulder with the cambered bar. It was because I lost my tightness and the shoulder was stretched past its capabilities. I'm still trying to get it back to normal after a year.