OK - some fine anorak contributions here.
My 2c worth is that when turning onto the arc you shouldn't turn 90 deg as this immediately puts you on a tangent to fly outside of the arc.
If you are intercepting from outside the arc, make the first turn 80 deg, and if entering from the inside, make the first turn 100 degrees. Then, by holding your heading, let the DME slowly count down to about 1 mile inside, and then count back up to the proper arc distance. This should conincide with full deflection, so twist another 10 degrees and turn another 10 degrees and so on.
