I tool a look at Pauls variable tone curves, and it is an interesting approach to change the color of the print by not using the warmer diluted carbon inks, or using the EB-6 curves in conjunction with the "k2" variable tone curves. I did a similar thing with 5 dilutions from the MIS inkset and a single channel of a Jon Cone shade 5 selenium that I used as a toning ink. It didn't have as drastic an effect as blending a full k3 selenium set with a k3 Eboni set, but it still make a slightly more neutral print.
Richard Boutwell