This is what I want to do I am installing a vacuum pump as I now have the car so it will go so now I want to stop. I am thinking about hooking it up to the brake light switch any reasons why I should or should not do this .

Thanks in advance for any info.

Unless you are fabbing a setup yourself, do what the instructions say to do.

You want vacuum in the booster BEFORE you touch the brakes, so hooking it up to the brake lights is a bad idea.

Just power it by a keyed source and use a vacuum switch to turn it on and off on the ground side (might need to go thru a relay to protect the switch from too much current).