The Yakima Cargo Box I own is a RocketBox Pro 14. I used cables, pulleys, and a winch to hang it right on top of where I park my car. When I winch it down, it lands right on my car’s cross bars.
The box fits well on top of the opened garage door. You can see that and the winch on this pic:
On this pic you can see the pulleys and cables:
This final pic has the car right under the box:
This project was a lot of fun; it involved pulleys and a winch! I thought I’d share this in case someone’s looking for ideas.
Pedro Liska 
Now this was a useful article! Using the roofbars was nothing I have thought of before. I usually leave my best cargo box left on the side, which is an expensive object to damage!
Any way to get a parts list for this project?