Youtube member Sitha Puth shares his DIY built to power a GoPro Hero3 from a Canon LP-E6 battery. Instead of powering the unit from the USB port, he's decided to craft up a power source from a Canon LP-E6 battery plate, step down converter, and GoPro dummy battery AC DC Adapter.
The build comes just in time with the new Protune 2.0 FIrmware Update packed with features that makes the GoPro Hero3+ (black edition) feel like an entirely new camera. Here's the build video.
Eventually Sitha will mount this to an inexpensive GoPro Hero Cage (he currently has on order). His build leaves access to all ports along the side of the Hero3 / Hero3+ camera so that you have full access to the Microphone input for better audio capture, or HDMI port for video output.
[Update Videos with Instructions on Build]
Here are the products in use.