Alan, do you mean Roy Harrington? When you print with a gloss optimizer with piezography you are printing a white patch with a separate profile thats only value is the ink limit set to the 255 value. When I print digital negatives with the piezography system i don't even worry about the GO—Just pass and that is it. (although i did use it for printing on gold leaf backed transparencies using the full k7 inks)
If you do want an ink to fire at 255 you would need to go into the .quad file and change the first value below "# INK Curve" from 0 to what ever value you wanted between 0-65535 (that upper limit of 65535 is 100% of that channel firing. It is like printing the 100% patch of that ink's separation image calibration mode with the ink limit set to 100).
In any case, I wouldn't worry about it. If you are making digital negatives just invert in photoshop and send that to the printer and don'tworry about trying to embed an inverting curve into the QTR profile.
Richard Boutwell