You can use a simple 90 degree bend and a short length of the wire poking through the bell crank, with a washer soldered in place to support it and bush it on the side and a washer, or something else soldered on the other side to secure it. I usually use a wheel collar to initially set things up and when I am happy with how everything moves and works, I solder the collar in place. Some use a 4-40 ball link at this pivot point also along with the flap horn and the elevator horn. Just be sure whatever you use, it is straight, square and smooth operating. I like to make the bell crank pivot as bullet proof as possible, as it is very difficult to get in there after the model is completed for any service or adjustment. Lots of ways to build in access to the flap and elevator horns for trim adjustments, but not so for the bell crank with out major surgery.
Type at you later,
Dan McEntee
LET"S GO BLUES!!!