I think that for B&W you can determine exposure on the cyan channel, but yellow and magenta filtration for VC paper aren't so straightforward as setting up channels for yellow and magenta, since the goal is different from the goal with color. I think you would have to have a way of reading, say, a Zone III and a Zone VIII spot on the negative, and determine the filtration based on the difference between them. Anyway, I'll hunt around and see if I can find the manual, and see if it says anything about this.