Unfortunately, he changed the part to an easier version in 1975. Until this day he only plays a "light version" of the amazing lick he did on the studio version. If Ry Cooder said he should have song credits for HTW, I'm sure he's talking about that lick. It would not be a surprise if Cooder wrote that (as he did on lots of licks on the Let It Bleed album).
The lick is easy to play. No pick. Use your thumb and index finger on the G-string and light E-string and slide away