Flight control trim for joystick control

[Malsheck]

While bringing a shuttle in with my joystick (I had been using the keyboard up until now) I found that I needed a way to adjust the pitch trim using the POV control on the joystick. After going into the input settings I found there was no way to assign trim to anything. I'm pretty much stuck having to go back to the keyboard mid flight if I want to set the trim, or just deal with the aircraft pitching down each time I turn. Is there a mod or work around that addresses this issue that I haven't found? Any help would be greatly appreciated.