My view of his technique...

It depends what record you´re listening...but basically he does a lot of
sampling from vinyl records (no shit!). Im not sure if he has recorded any
live bass playing in studio, probably not that much, if at all.

He used to use Sp-12/Sp-1200 with s900. I believe he uses the
lowpass filters of the s900 to get the basslines or he chops them
and plays them loosely with the drums.
Nowadays he has been producing with 2000xl.

Hope this helps and please correct me if Im wrong.