QTR-Quadtone RIP

I'm wondering if anyone has tried split toning effects with qtr and how they
went about it.

I'm using UT7 and wish for example to create a print that is _slightly_ cool
in the shadows and midrange and warmer in the highlights. 

I thought the best way to approach this would be to use a basic warm curve
and then introduce the cooler magenta inks as toning curves (M as toner
curve & LM as toner curve 2).

However I can't seem to get the toner curves to start at anything other than
100 no matter what I put in the density box for these inks. The two toner
curves also almost completely overlap each other so it doesn't seem possible
to have one toner ink smoothly graduate into the other.

Any ideas?

Thanks
Howard