[apfubar]

Here is how I have my 966 setup:
- channel input config: pump channel - inh (removes it from any switch)
- Programmable mixes:
1. On > pump channel, rate: 100/100, offset 0, switch on (this sets zero to -100)
2. Source/input channel > pump channel, rate: -100/100, offset 0, trim inh, Switch on
(For each hydraulic valve you repeat point 2)...

I suspect the -100/100 though is the key.

Cheers,
Ap