1. Get a beer.
2. Pop the hood and locate a vacuum line. Vacuum lines a usually black soft rubber tubes, and the vacuum tube size you'll be looking to tap is smaller. DO NOT pull one of the big black vacuum tube hoses.
3. When you find a smaller vacuum line, you will cut it in half using a razor blade or any other cutting device.
4. Once you have cut it in half, you will then put a vacuum tee in the two sides you cut to re-connect them.
5. From the extra side of the vacuum tee, run a new piece of vacuum tubing (short) and then slip the nylon tubing provided with your gauge into the open end of the vacuum tube, securing it with a zip tie. OR if your gauge came with a tubing adaptor, place that over the extra side of the tee and place the nylon tubing into the other end.
6. Locate an access hole in the firewall of your vehicle, and run the nylon tubing through that. If your vehicle doesn't have a hole or you can't locate one, you can drill a small hole. Be very careful if you decide to drill your own hole, as you can puncture other wires or mess up other things down there. Make sure you place a rubber grommet in the hole you drill around the tube so that there is no change the tube can be punctured or damaged by the newly drilled hole.
7. Once you have the nylon tube into your vehicle, you will then run it through your new gauge pod, leaving the tube hanging out of the pod hole.
8. This step is very important. You will use the open end of the nylon tubing in this step and place it into the provided Ferrule, tightening it until the tube is secure but not crushed. From here, you will screw the other side of the Ferrule into the back of the gauge. It is recommended that you use plumbers tape on the grooves to secure them and make them leak free.
9. Secure the gauge into the pod, and you're all done. Start the vehicle up and if you got a boost/vacuum gauge see if it reads vacuum. If it does, then you did the install correctly. Make sure you listen and check for leaks, if you did something wrong with the install you'll know usually right away as vacuum leaks can cause all sorts of problems.