Good question (to me). I've been wondering for months if anyone has ever tackled just the bassline (and it's not as intuitive as it may sound). I've always assumed that when ready, I'd read from the bass clef of a Piano arrangement (which I possess, but have hardly tackled). Not sure how anyone could tackle both the bassline and the melody of this monster-beast classic at same time. :-) Even on keyboards it seems like nearly an impossible goal. :-)
Note - the actual title is "Linus and Lucy," originally composed/performed by Vince Guaraldi. I also love George Winston's performance in tribute to Guaraldi, but Winston has an edgier improvisation.
Edit: This link (if it works) on Active Bass lists bass tablature for Linus and Lucy.
http://www.activebass.com/tab/artist.asp?i=371 Not sure if you were interested in the Metallica version. Problem - no "bass tablature" of this title that I can find currently seems to be supported...
Edit: Would love to see two bassists tackle this song in live performance. Michael Manring on a Hyperbassed bassline, with perhaps Jean Beaudin performing the melody on his 11-string...