QTR-Quadtone RIP

Hi -- I'm using QTR to make digital negs for carbon and I'm wondering if anyone can tell me how to flatten the slope of the left side (zero end) of my QTR curve. I'm using three inks and I'd like the first to build up gradually because the dark patches on my print fall off too fast from dmax. Or, even better, is there a way to have a little ink in the mix even at zero on the curve? Everything else is perfect. Thanks in advance! Scott W