As Tony said, you may not want to risk your ignition box. It is small and the components are quite delicate.
If you should leave a gap too large for it.... it will fry itself near instantly.
I simply remove the plug, make sure the wire is on all the way and hold it's threads against a head bolt and turn the wheel slowly with my other hand and rock it back and forth to establish where it actually fires, while looking for the firing point on the clockwise turning of the wheel.
(hold plug by the hex nut part of it and as long as it is touching the head bolt, you will not be shocked)
Last step.... Have fun...!