well i'm not 100% sure if this is what you want to do, but I have a game I'm working on that flings things.
so yea if this is what you would like to be able to do... to "throw" something and have it behave with physics.. basically what you want to look at is:
apply physics impulse towards position.
impulse - (distance(Box.X,Box.Y,Touch.X,touch.Y))/10
x - touch.X
y - touch.Y
image point - 0
you'll also want to have drag/drop working as well.. though i rolled my own so I'm not sure if the drag/drop behavior would conflict with it.