Replacing Mission Planner Pos with own Pos. system

Hey All,

My Drone is able to fly to the Pos. i tell him via Mission Planner. What i would like to do is, i would like to replace the GPS Pos with the Pos. of my Positioning System. How can i do that?

My Idea was maybe i could rewrite the Controller Code? But how can i get acces to it?

Yours Rubics