Here’s the gist of it.
So, basically I figured out that if you “manually” tune 3 curves to print three negs that make up your image, and that image is a standard 129 step PiezoDN target, you can read that target and literally use just that 1 measurement set to linearize all three curves. Because all three curves combine to make the 1 target, methematically linearizing all three of those curves with the measurements from the 1 target should linearize the final print.
The hard part is manually tuning the three curves in the first place. You use the Piezography Curve Adjustment tool for this. Really you can simply tune the three curves exactly the same way you would tune the original photograph in photoshop to print each negative (shadows first, then mid-tones through shadows, then highlights correct?)
The first neg would have to blow out the HLs and have open shadows (so very light).
The second negs would need to still blow the top HLs and be slightly darker over-all.
The third neg would need to be very light/open in the shadows (while maintaining dMax on the darkest 2% to keep tonal separation) while bringing the highlights in.
Combination of the three should give you no tonal reversals on the 129 steps and allow for linearization.
After linearizing all three curves from the first target you should be able to print a totally linear image.