Vuforia Multi Object Collision

I'm trying to make a sample app where I have two separate image targets with two separate Models, each with their own animation.

I what I'm trying to do is have them play their animations when the get near each other, and stop when they are no longer close to one another. Since neither of them are 'player controlled' I'm wondering if simple box colliders will 'trigger enter' and 'trigger exit' a la http://www.youtube.com/watch?v=9vAAnt2uboU If not, how do I get them to trigger each others animations?

Thanks