Sorry there is no way to use binding to get the position. I'm not sure you would want to use binding for the best performance.
If you do really need it though, you might want to take a look at Pete Blois's behaviors for Box2d physics. I'm pretty sure he has all of the binding working for position.
Here is the link - http://www.blois.us/blog/
To do this with Farseer and the Physics Helper, you have a couple of options:
- use and extend the behaviors for ApplyForce, ApplyRotation, etc.
- use the PhysicsObjects collection to get the Farseer Body position
int x = _physicsController.PhysicsObjects["ball"].BodyObject.Position.X;
- use the PhysicsSprite.uiElement property to get at the actual XAML element in the game Canvas
Hope this helps