CCI base with a little bit of white for underbase, then print the colors as if you are printing simulated process.
underbase will not be real white so you will need a highlight for the areas that are supposed to be true white.
the only project we did like that had colors on it that were muted and did not have to be spot on. So it is possible that your final image will be a little darker than if on white. This is where the amount of white in the underbase mix will come into play. I would start at 20% and work your way up to no more than 60%, but would start with 20%.
Also, triple strength might not be a bad idea. I have some here and will test when the time permits.
pierre