i think its quite simple.

or i might be missing something..
but its as easy as setting your vari-pitch?... or do a bit of work ahead of time and time stretch
i had fun doing what your doing with daft punk's homework album.
the hole cd seems to be only 2-3 diffrent beats
and the isolator on the 808 works really good in conjunction with playing 2 of the same beat
cheers
shawn