As far as I know, the 240D does not have the governor idle screw. If your dash mounted idle adjustment is not working, then what you should do is open the hood and watch the stop lever while you reach in and turn the knob on the dash. If the cable attached to the stop lever moves, then you can adjust it at the mounting point on that end. If not, then it has probably come apart at the knob.
Edit:
This thread has a picture of the stop lever. Yours should be similar but not exactly the same. Notice the two cables? One goes to the cruise control actuator mounted on the inner fender. The other is the idle adjustment. Both are adjustable at that mount in the lower left corner of the picture.