I am almost certain that Willy uses this open tuning, however, I think the third string 
be tuned up a tone to an A rather than G for some songs such as 'Hard Hand To Hold'; 
not too important here though.

The song is littered with different variations on one theme, such as changes of rhythm 
sections of strumming rather than picking. After watching an acoustic version of this 
I have presented what I think to be the most important theme below.

It ought to by played on an acoustic with metallic finger-picks to provide a clear yet 
sound.

Tempo: 200 bpm (approx)

Main theme:

1: D|3/5---3-----0---|----------------|3/5---3-----0---|----------------|
2: A|----------------|3/5---3-----0---|----------------|3---5---0-------|
3: G|----------------|----------------|----------------|----------------|
4: D|----0-------0---|----0-------0---|----0-------0---|----0-------0---|
5: A|----------------|----------------|----------------|----------------|
6: D|0---------------|0---------------|0---------------|0---------------|
     1 & 2 & 3 & 4 &  1 & 2 & 3 & 4 &  1 & 2 & 3 & 4 &  1 & 2 & 3 & 4 &

1: D|3/5---3-----0---|----------------|------0---------|----------------|
2: A|----------------|3/5---3-----0---|--0-------0---0-|------0---------|
3: G|----------------|----------------|----------------|----------------|
4: D|----0-------0---|----0-------0---|----0-------0---|----0---0h3-----|
5: A|----------------|----------------|3---------------|2---------------|
6: D|0---------------|0---------------|----------------|----------------|
     1 & 2 & 3 & 4 &  1 & 2 & 3 & 4 &  1 & 2 & 3 & 4 &  1 & 2 & 3 & 4 &

Try and let as many notes ring out as possible

Sample Variation:

1: D|3/5-5---3---0---|----------------|3/5-5---3---0---|----------------|
2: A|----------------|3/5---3-----0---|----------------|3h5-----0-------|
3: G|----------------|----------------|----------------|----------------|
4: D|----0-------0---|----0-------0---|----0-------0---|----0-------0---|
5: A|----------------|----------------|----------------|----------------|
6: D|0---------------|0---------------|0---------------|0---------------|
     1 & 2 & 3 & 4 &  1 & 2 & 3 & 4 &  1 & 2 & 3 & 4 &  1 & 2 & 3 & 4 &

1: D|3/5-5---3---0---|----------------|------0---------|----------------|
2: A|----------------|3/5---3-----0---|--0-------0---0-|------0---------|
3: G|----------------|----------------|----------------|----------------|
4: D|----0-------0---|----0-------0---|----0-------0---|----0---0h3-----|
5: A|----------------|----------------|3---------------|2---------------|
6: D|0---------------|0---------------|----------------|----------------|
     1 & 2 & 3 & 4 &  1 & 2 & 3 & 4 &  1 & 2 & 3 & 4 &  1 & 2 & 3 & 4 &


The song ends with the first two bars of the main theme played, proceeded by an open 
and a couple of hits of the third fret of the sixth string, shake that note around and 
out with one last open chord.

Please feel free to lend any constructive criticism.