There are a couple of different ways to install it. Either the top hinge or center hinge work best for larger graphics. The top hinge is the method that Dave talked about and the center hinge is done by positioning the graphic with backing exactly where you want it and apply the masking tape from top to bottom in the center of the graphic. Then starting at the middle remove the backing from one side and squeegee from the center out. Once that is in place then go back to the center and remove the rest of the backing work the other direction.
If you have smooth sides with no rivets or screws to cover you can also use an application fluid such as RapidTac to make the job easier. The application fluid works great with solvent based adhesive which is what most high performance vinyls use. Just try to avoid application fluid when rivets or screw heads are involved. It is hard to squeege the fluid out from around the heads and can leave you with air bubbles. The use of application fluid is more forgiving for the novice installer. It allows you to reposition the graphic in case of a misalignment or large air bubble.
www.rapidtac.com has a couple of how to videos that may help. Also the following youtube has a quick tutorial.
Mark