I'm doing mine in SC. I did some more last weekend at a friends farm. He like I had read the procedure backwards and forwards, but had not performed it, seen it done and couldn't find anyone willing to show him. His experience mirrored mine in that we both seemed to be able to found people "who knew someone" that could and would show us how, but they never actually materialized.
Judging from the responses to this thread as well as the number of threads in the archives there is obviously great interest out there. I finally took the plunge and have been having great results, but still a few questions mentioned before.
Some things I did learn - while I didn't have much trouble locating the correct spot for the incision, my friend did. It is not a question of unfamiliarity either - he raises chickens for both eggs and meat, and processes his own birds and has been doing so for years.
I don't think this is an intuitive process for most people. In finding the correct incision site, I found that applying pressure with the tip of my thumb just above (towards the middle of the bird) the thickest part of the thigh allowed me to feel the abdominal cavity under the rib cage. From there it was a simple matter of "counting up". The lower rib on some of the breeds and birds we did was deeper than the upper ribs and required a little pressure to feel. This is where my friend kept missing.
The other mistake I noticed was too little force exerted in making the cut. We were using surgical scalpels (which I highly recommend) - there are or at least appear to be 2 separate layers of muscle fiber between the skin and the actual abdominal cavity as well as a membrane. I myself was very nervous at first about slicing through into internal organs when making the cut. This simply didn't happen, there is ample space between the organs (on a bird with food withheld) and the skin, subcutaneous muscles and membrane. I bird did get loose during the day and was confused with another that had been eating. The intestine was swollen throughout the cavity in this bird - I could not proceed so we sutured and returned that one to the other flock (where he is alive and well).
I will post pics or video of the next day doing this, I hope this helps.