General information for x900 Piezography K7 can be found here: http://www.piezography.com/PiezoPress/technical-support/epson-pro-4900-7900-9900-installation/
x900 Digital Negative curves and ink shade placement can be found here: http://www.inkjetmall.com/tech/showthread.php?639-Minimum-number-of-inks-for-making-digital-negs (look on post #5).
I included instructions for installing curves on both Mac and Windows platforms below.
HOW TO INSTALL NEW CURVES FOR USE WITH QUADTONE RIP
To install a new curve to use with QTR, you will need to drag and drop the curves (NOT the FOLDER containing the curves, but the individual curves themselves) into the following folder location:
(Windows) C:\ProgramFiles\QuadToneRIP\QuadTone(Your Printer Model)-K7[B]
(Mac) [/B]/Applications/QuadToneRIP/Profiles/(Your Printer Model)-K7
NOTE: With Mac users, you must uninstall your Quad printer model then reinstall it using the install.command located in the same folder you placed the new curve in. You will also need to restart your printing application if it was open when installing new profiles. This will show the new curve in QuadTone RIP. You will not lose any of your previous curves when you uninstall the printer.
NOTE: When using a printer model with MK and PK cartridge positions (3800/3880, 7890/9890 and 7900/9900), a Black Ink Change must be preformed to change between matte and glossy compatible black inks. Make sure to use the appropriate black ink for the paper and curve you’re printing with.
I hope this helps.
Best regards and happy printing~ Dana