QTR-Quadtone RIP

Hi there,
I've browsed the archive but most of the information there is too sophisticated for me at the moment.
I'm using an Epson 4000 with Semi-Gloss Photo Paper and the standard (ultrachrome?) inksets. I can't get a quality mono image with the epson driver so I'm trying the quadtone RIP.
It certainly gives me a great neutral image if I just select a single neutral curve. However I find it a bit cold so I'm trying to blend it with the sepia and the carbon (which looks much the same as sepia to me).
However even if I set the first neutral curve to 100% the warmer curve seems to over-ride it. Same with choosing split tone - it makes no difference.
I'm sure I haven't given enough information here, but that's because it's new to me and I'm not sure what I need to offer up. 
I am using  mac (10.4) Photoshop CS and trying to a print a greyscale image (single channel).
Your help is much appreciated.
Mike