Zahnartz62,
If I understand correctly you are trying control in game mouse cursor with X-52 Throttle mini-stick, right?
If you already move the cursor with mini-stick, to click with X-52 Throttle mini-stick middle button try:
Go to (il-2:CloD) Controls > Aircraft > Keys tab:
And at the end of the list select the Event "Mouse Control":
For default it's assigned to "Mouse Left (button),
you will not change that,
but will create a new command for this function (Event).
After select "Mouse Control", click in "NEW".
In the new window, press in X-52 Throttle mini-stick middle button.
Is expected to be displayed in the new window the name assigned to X-52 Throttle mini-stick middle button, something like "Joystick+Key....
If it works -
the game recognize X-52 Throttle mini-stick middle button - you will end with two commands to the function "Mouse Control",
one with "Mouse Middle (button)" and another with X-52 Throttle mini-stick middle button.
And can use both alternately.
I test this above with Tm.T-16000M joystick and the joystick button (Joystick button 10) assigned to "Mouse Control" work fine.
A nice feature of il-2:CloD GUI is allow make copy and assign different keys/buttons for "Event".
Sokol1