Digital BW, The Print

I just ordered a CFS and Ultra-tone inks so that I can give them a 
try on my Epson 1200.  It is awesome how Paul has put the effort in 
to create us all curves for these inks.   How even it seems that one 
may want to modify the curves to suit there own needs.   Are there 
any good references on the theory be hind these curves that might 
help me and other understand how they are arrived and how best to 
modify them?

Thanks,

David