QTR-Quadtone RIP

Hi All,

I'm looking for a suggestion on how one can edit an ink curve in
Photoshop. Is there a chance to export created curves for further
tuning them in Photoshop? I have a need to adjust the sepia tone
produced by the RIP to match my existing prints. While I got a good
result in shadow and midtone areas I am struggling with the
highlights. My existing prints have no white at all in highlight area,
when I print with the RIP I'm getting white there. Looking at the
curves I can see why but I could not find a way to adjust them. I'm
hoping to load curves for LM,Y,LC instead of copying them from LK. 

Please advice.

Thanks,
Igor.