I never did it with the engine running. Just a little trial by error. It was 11 years ago, so my memory of details is weak. I think a full turn gave something like 5 -7 psi change to the cruise oil pressure. I would check the log book entry for you, but it is packed in the evacuation box right now.
The one thing I DO remember is that if you don't safety wire it, it can unscrew and drop the pressure again. The first time that happened, I just thought I was dreaming. The second time, I said, "OK, it must be backing out again", safety'ed and it has never changed again.
The adjusting nut is held fixed on the regulator shaft with a hollow roll pin. I just fed the wire through the center of the roll pin.