Ziegler-Nichols tuning for APM2.6

Hi Guys,
This my first post on the site, I have been a long time reader.
I am looking to tune my quad using the Ziegler-Nichols method. The problem is that I need to get feedback from the APM to be able to tune it, I need to get the Lag value and the slope of the response curve, Is there a way of getting this info?
Has anybody else used this method?
Thanks in advance for any help.
Tommy