I learned it in ordinary G but using a Van Ronk sort of alternation of the high E G note and the (B string 3rd fret) D note.

The chords are:

(G)Here's what Doctor John, the baptist (D7)said;
This is what old John the Baptist(G)said.
Here's what John the Baptist(G7)said,
(C)Just before he (C#7)lost his head
(G)C'mon, give (E7)me those (A)separ(D7)-ration (G)blues!

Hope this helps.

A