Well, this song sounds like synthesizers, but John Greenwood has said in interviews 
that it was made by guitars. However, my speakers rattled when I turned up the bass, and 
there is that ominous line, so I inferred that there must be bass on this song. Also, about 
the holding notes (~), these are long holds, not long in the traditional sense, but ranging 
around 15—30 seconds, which is  harder than it looks.

From the alum _Kid A_

FIG. 1

G————————————————————————————————————————————————————1~—————————
D—————————————————————————————4~————————————————————————————————
A———4~——————————2~——————————————————————————————————————————————
E————————————————————————————————————————————————————————————————

FIG. 2

G————————————————————————————————————————————————————————————————————————————————————
D————————————————————————————————————————————————————————————————4~——————————————————
A———2~————————————————————————————————————4~—————————————————————————————————————————
E————————————————————0~——————————————————————————————————————————————————————————————

FIG. 3

G——————————————————————————————————————————
D——————————————————————————————————————————
A———1~—————————————————4~——————————————————
E——————————————————————————————————————————

This bass tab will be of no use to you unless you actually consider playing "Treefingers" 
again. Have fun!