I’m afraid you are going to be limited if you’re not prepared to pick up a soldering iron. You can get pots with pre-soldered cables (like this http://www.ebay.co.uk/itm/Pitch-Con...om-Zenmuse-Alexmos-Tarot-Gimbal-/221364804017) however to connect them to the circuit that controls the tilt you have to dismantle the transmitter, de-solder the old trim pot and solder the wires from the replacement pot to the main board. As far as I am aware there is no ‘easy’ plug and play solution.
Your only other option to make things more controllable would be to replace the stock transmitter with a nice new shiney Futaba FASST (the easiest one to implement as it binds to the existing receiver) or go one step futher and replace the receiver and transmitter with a Futaba FASST or FHSS system. These transmitters allow for configuration & programming of parameters which should allow you to do what you need.
Your only other option to make things more controllable would be to replace the stock transmitter with a nice new shiney Futaba FASST (the easiest one to implement as it binds to the existing receiver) or go one step futher and replace the receiver and transmitter with a Futaba FASST or FHSS system. These transmitters allow for configuration & programming of parameters which should allow you to do what you need.