2 piece magnetic switch?

I'm installing an alarm on my '89 Honda Civic hatch and would like to use a magnetic switch on the main relay. I've read about other people using the DEI 8600 but I think it is Normally Closed and if I understand correctly, I need a Normaly Open switch.

Basically, what I want to do is what I read on another site but which did not provide details:

This installer hid a 'magnetic' switch on the (-) fuel pump line under the carpet. When he leaves the car, he simply lifts a magnet off the carpet and the fuel pump gets killed. When he gets into the car, he places the magnet in a "sweet spot" on the carpet which closes the switch and re-activates the (-) fuel pump line. He does this automatically and 'secretly' and not even his passengers know what he is doing - better than a hidden switch which your passenger might notice you activating!

I want to emulate this on my car but with the (-) main relay ground which kills the ECU, injectors, fuel pump and a couple of other sensors. Any suggestions as to the type of switch I need and where I can buy it? Since I'm disconnecting a low amp ground, the switch does not have to be high capacity.

It has been many years since I have used one of these, you will need to check and make sure that they still have a Normally closed and a normally open connection.

http://www.radioshack.com/product/index.jsp?productid=2419297

They do make similar alarm switches that are Single pole double throw. 

http://www....com/c-74-contacts-door-windows.aspx?&mfrid=7