I see. But that does not take into account the scale, rotation or offset of the image relative to the body it is attached to. I'm afraid I'm gonna have to refer you again to the post I linked to above. The important part is:
"In the RUBELayer class, the functions loadImages and setImagePositionsFromPhysicsBodies perform the getting of the necessary info from the JSON file, and then the positioning of the sprite to the current location, rotation, and scale of the body."
I really think you need to drop the idea of using the generated C++ code, because it will get you nowhere fast. Did you try building and running the cocos2d sample project?
You might also like to watch this video, which shows all the steps for setting up the loader with cocos2d, it takes about 30 minutes:
Using RUBE with Cocos2d (2/2)