Yes I have a theory but havn't practiced this, it's off the top of my head, I will be suprised if you havn't thought of this already, but.. :-
First set the camera to move with the mouse, x for left and right(3D x axis) and y for forwards and back (3D z axis), with the middle mouse button(4) for up and down (3D y axis), thats the 3 axis covered for the camera, of course tilt and roll are other things to bare in mind, I am presuming this is not needed.
so to move the object you can click and hold the left mouse button and while held you move the object with the mouse the same way you would with the camera, once you let go of the left mouse button (or the one assigned to the object control) the object stays in that place or does whatever you code it to do after releasing the button and you go back to the camera control.
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