Go here to take a look at and buy the mounting rig and sync cable on sale for $99.
The SUPERHERO 3D Rig | 3DGuy.tv.
Al Cadullo is a professional 2D/3D cinematographer who has found the GoPro’s provide a compact and excellent quality 3D rig when mated with each other. GoPro sold a synchronization package for their Hero2 but the Hero3 version has been delayed. So he’s come up with his own product.