I watched a You Tube of Jonathan Edwards playing it. Seems like he may use a open G tuning, D G D G B D.

Seems close if you start with open G then onto Sixth and Fifth string fretted on the second fret and the 2nd string fretted on the 1st fret and then move up two frets and then back down etc etc ...............there may be more to it but maybe that will give you a new way of looking at it