[Coco] OT request

[Dave Kelly]

This is the only group of electronic people I know so this is where I 
ask this kind of question.

I want to hook my trailer into the panic alarm on my car. What I would 
like to happen is;
The door lock button on my key ring would activate the alarm device.
The door unlock button would deactivate the alarm device.

The alarm device would be attach to the trailer. When I lock the doors 
of the car to go fishing, the alarm device is turned on.

Someone comes along and starts fooling with the trailer. A mercury 
switch causes a signal to be sent to the panic alarm on the car cause it 
to go bonkers.

I return to the car, push the red panic button on my key ring and the 
panic alarm goes off, push the door unlock button the the alarm device 
is deactivated.

OR

Noone bothers the trailer and I return and push the door unlock and go home.

So I need:
Circuitry, match box size.
Teachable.
Water proofable.

Anyone know is something like this is available or schematics to build one.

Thanks
Dave