you might want to take a look at my two digital negative systems. The QuickCurve system is for UCK3 printers, and the QuadToneProfiler Pro DN system is something I released just a few days ago for profiles with more than 4 gray inks (and insets that don't use color inks at all). I came up with a way of partitioning the grayscale that doesn't use qidf files or the QTR install command to generate the quad curves so everything takes on a much smoother curve, and does not require such an aggressive correction curve in the linearization step.
Here are some links:
I have not been able to test every process under the sun (some pun intended) but in theory, the approach is flexible enough to work with any process. I hope to get my feet wet with carbon printing this winter, and then dive back into salt printing on gelatin-silver paper again to test out these systems and start to build better starter curves for different processes to use in future updates.
Hope that helps,
Richard Boutwell
http://www.richardboutwell.com/