Well, Rasta, not sure if I can definitively help you out or not, but here goes:
I learned the song off of an Emmylou Harris record sometime around the end of the Civil War and I play it in C.
To start the song I finger and "Am" chord and strum it with much clarity letting the last note of the strum (the open E string) become the 1st note of the intro.
Then: as smooth as you can do it (while keeping the Am chord fretted) alternate plucking between the "open E" string and the "3rd fret of the B string"
You will end up moving a bit on the "B" string as you pluck the notes in this sequence E-D-E-D-E-D-C-B-C.
Then, after you play the last "C" note "punch" the following chords in order, and, when you get to the "C" chord start your rhythm and get into the song; punch "Am - G - C" in quick succession almost as "grace" chords. I think the Am and G chords are really taking the place of passing notes here but it makes a really nice "fat" sound.
God, I hope this some sense and works for you. I'm not really sure it makes any sense to me, but that's how I play it. Cheers.