Try QTR Build Script by David Eisenlord. You can download a folder, which contains the script, a 21 step wedge, and instructions, from his web site. http://www.davideisenlord.com/?p=229
After you build the curve you read input/output values in PS with Curves, and then just insert these numbers directly into the QTR profile with the GRAY_CURVE command, for example.
GRAY_CURVE="0;0 7;10 13;20 20;30 28;40 37;50 43;55 49;60 57;65 65;70 73;75 80;81 86;86 93;92 95;95 100;100"