Digital BW, The Print

I've just started using Quad Tone Rip with an Epson 4000, Windows XP
system.  Expermenting with Red River Polar Satin (a luster paper
similar in surface but a bit yellower/white than Epson Prem Luster) I
would like to get a cooler black color.

I have tried the QTR curves (for Prem Luster) designated
"UC-CBrightWhite-neutral", and "UC-ISmoothPearl-neutral" but there is
no ...cool version of either of these in my download for the Epson
4000.

Does anyone have, or know a simple way I can alter either of these
curves, or suggest another curve that will give me a coolor black
(something closer to UC-EEnhMatte-cool on Epson Matte Paper) ?

Thanks,
Ken