I was trying to find a way to have one piano play back entirely in quarter tones for a two piano piece, one tuned down a quarter tone. How would it best be done in Dorico without using the microtonal accidentals, since the piano won’t be reading off microtonal accidentals?
Just load two instances of the VST with one piano in each, and set the tuning to different values.
A quarter tone sharp from A = 440 is 452.89, and a quarter tone flat is 427.47, so you will need a VST where you can set the tuning in fractions of a hertz, unless 453 is near enough 452.89 to make no difference.