plugin help

[Mopar Madness]

I was wondering if someone was up to the challenge of making a plugin or modifying a plugin to make a plugin that's the opposite of the wwzone plugin, so shots only fire when a tank is off the wwzone.
For a while now I've had an idea for a map where the teamflags (or geno ) are in boxes guarded by lasers that are turned off when a tank on the other side of the field enters a wwzone, to encourage teamwork, but I dont have a clue on how to make or even add a plugin to a map, but I do have a friend who could add it if it's made, I just know how to make maps.