QTR-Quadtone RIP

Roy, here's a quote from your read me.  

"Print a stepwedge like the second one above, scan the step wedge and drag the
file of data readings on to QTR-Create-ICC... The created icc
file is used during printing to achieve a Perceptual Intent mapping from any
input embedded profile to the output. This scheme can be used with any type
of black and white printing such as Black-Only from the Epson driver or the
new Advanced B&W mode of the latest printers."

Does this mean that the profile is used for the Print Space?  And if so, how do you deal 
with the fact that you may be blending two curves?

Ed