Never really looked at the complex code of the mousejoint in physics. We did now for a tracking example - so the hands can knock around physics balls. It works with multiple hands so we can probably adjust it to multitouch mouse. And provide an abstracted class or function to handle this type of thing.
In this case targetLeft and targetRight are two points representing the center of the hands and we move balls around. So in the near future, we will make this easier.
The blue circle is moved by the other hand - which was busy taking the screenshot 