if i was making a jig, i would take a couple of boards, fit a hinge at one end and something at the other end that locks with a wing nut at your chosen taper. Then one goes against your fence, adjust to the desired angle, do up the wing nut and away you go. I can picture it better than explain it, but it should only take a few minutes to make.
Roger's suggestion of doing it freehand is probably as good as any. when i get my bandsaw set up, it is something i will need to try!