I purchased a remote controlled device called the Battery Brain (gold) from a Florida company. I installed the relay switch to my positive pole of the battery (had to cut a hole in the cover plate), then the other side to the positive cable.
This device comes with two remote devices that turn this relay off and on, effectively disconnecting the battery anytime you want. The Battery Brain has two functions, for security as noted, and it will sense a slow drain (after ignition is turned off) on the battery (if you leave your headlites on, for example) and kill the connection. I think I paid about $80.00 for the device and their phone support is good. It sure gives peace of mind when you walk away from your "baby".
check it out:
http://www.batterybrain.com/