How to make a Neutral gear with BallShifters?

[TheFrozenSlink]

Our team was planning on possibly making a slingshot style launcher, where a motorized winch pulls back and arms our cannons and then we would shift into a neutral gear to disengage the winch and, and the ball would be fired, similar to 1114 in 2008 (Im sure you've seen a lot of them in the past 5 days).
I was wondering how difficult it would be to convert the 3 Cim BallShifters our team ordered so it would have a neutral gear, or if there is a better way to accomplish the same task, that wouldn't require taking apart our gearboxes?