It's not really what you're going to want to hear but I REALLY strongly recommend you look at getting a tool like Axis and Oh or Spad.next to handle complex control setups, not just for this plane but for any plane in pretty much any civilian sim.|
They cost money yes but, for me at least, I genuinely would not want to fly a sim without support from them.
But in this specific case, I do have a Fly With Lua script here which maps the flaps specific to buttons, you can probably use Joy to Key or Joystick Gremlin to map axis positions to buttons and trigger them, or alternatively use that as a base for controlling directly from an Axis setting.
CJ525_Custom_Commands.lua