I don't think the Lethal Box works like that though. The battery negative is always touching the box because they are screwed in. I haven't actually tried it, but its definitely on my list of mechs to get. Its got a top mounted fire switch on the opposite side from the atomizer... kind of like a Dimitri. There are $30 clones available now. I don't have one and can't find pictures of the switch internally, but this is how I bet that it works:
The battery under the atomizer is not actually touching the connection to the 510 pin, thats why the box is a little bit higher up on that side. This battery is simply connected to the other batteries. The battery closest to the switch is just under a piece of metal that is connected to 510 pin. The switch pushes the metal down to supply 4.2 volts.
It's safer than cherry, the body looks insulated I think? Looks to me the batteries are connected to the centre pin at the positive end, the negative end is connected up to the swtich, when the switch is pressed, it touches the metal piece on the 510 connection (internally) and completes the circuit
ADD: The Lethal box is a tri-battery, you could easily draw 60amps (20A each) without stressing the batteries, that translates to 0.07ohms, about 240W, without pushing the batteries too hard........ I'll still stick to sub 50W heh.