A while ago I ordered a pair of cables for this project. They have the proprietary connector on one end which will plug in to the accessory port on the camera. The other end is a standard USB connector that will plug in to my interface PCB. I bought two cable with the plans to chop the USB end off one of them so I could wire it in to my prototype. I recently discovered some USB breakout boards on eBay. I will be able to use the cables as is so I can keep both cables intact.

The breakout boards, and some USB connectors, have been ordered and have already been shipped as of this morning. Once the items arrive I will have all the parts I need to make a prototype of this project.