An exact amount, well, it would need some calculations. But yes, it can be done.
If you want to move the piston up by a different amount than moving it down: yes, that can be done too. You'll have to use two "intermediate" valueParms, set their min/max limits to 0 and 1, and -1 and 0 respectively, slave those valueParms to your master dial(s), and slave the actual movement parameters of the piston to the intermediate dials, at different "deltaAddDelta" values.

Moving one piston up while the other moves down: slave both movement parameters to a master dial, one at detlaAddDelta=1, one at deltaAddDelta=-1.

The pen is mightier than the sword. But if you literally want to have some impact, use a typewriter

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