Camera button belly

What is the best way to weatherproof the plastic box for a motion sensor originally intended for indoor use? - quorum g4567

The motion in question is a good infrared detector Quorum (RR-150/A-160/G4567) powered by a 9V battery, DC 5V, which gives about 1 second when it is triggered. The thing is, I, too, such as welding leads to the battery contacts, so that you can through a wall transformer to power. Comes in a plastic box that is completely waterproof, and as far as I've seen, either by using a glue gun to all seams and holes, or put everything in another plastic (Plexiglas or seal). For the moment I am very concerned about leaks concerns, but it is possible that the temperature is a problem also, I think. The sensor is used in a temporary outdoor installation of six months this summer.