A good soldering iron is required, I have done it (added larger wires). There is always the chance of damaging something, just don't overheat the circuit board.
Why not buy a traxxas male plug and solder it on the mm leads?
I aready have the lead connected to the male traxxas it would faster to just solder on the power leads to the MM ESC, but if I would fry the ESC while soldering that would be a pricey lesson