removal of flywheel ???

[rexraider]

I am new to the outboard motor seen and I need to remove the flywheel to get to the points.
how do I lock the the flywheel in place to remove the center locking nut and will I need a impact wrench.
"58" Sea King 5hp and a "55" Scott Atwater 7-1/2hp if different.

 

[rexraider]

thank for the info worked like a charm, one more quick Q. needing torque specs