With percussion do you mean the attack time on 4', 2 2/3' and 2' as discribed on page 101?
You can save two different organ setups as seperate user voices and make a split between Left and Right voice (p.105), but if you use the styles as well, there is not much room for two voices. Esp. for organ, where you easily play over 3 octaves with the right hand.
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drdalet