Btw,
The reason you need the box is because the battery is full of acid. During a bingle, if the battery breaks apart, you'll get splattered with the stuff. Not nice.
The dry-cell batteries are just as good (unless you've got a kick-ass stereo), don't need the battery box, and can be mounted at almost any angle - except completely upside-down.
So if all you want is to start the car, and run the alarm for a few days at a time, get the smallest Odyssey. Its small, light, can be hidden, and works.
peter