You use MSEGs for this. Unfortunately, the set loop points in Osc3 appear to be ignored. You can set loop points using MSEGs, but it's not a trivial exercise to get it working properly.
Edit: I've made a simple patch to show some of the modulations that are possible.
Here MSEG1 sets the sample start position. MSEG2 fine tunes this. Note that these MSEGs are set to 100% and 1% in the respective MSEG sections. Osc1 (a ramp wave) then modulates MSEG2 amount in a velocity sensitive manner. This has the effect of scanning around the point set by MSEG1+2.
MH Drum Bass.zip
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