I don’t know if it can be done with a output map. Maybe it is easier to store your curve in a .lut file and load that, either as a rendering postprocess or a lut map. I have found this converter - I did not test it but maybe you can give it a try.
/edit: It’s even easier, since Photoshop can export LUTs by itself.
I cant do it in post since it has to be only applied to certain nodes in the shader network.
For some reason the luts created in photoshop give me different results in max (too bright in this case).
It worked fine on a simple B/W gradient but doesn’t work as expected on bitmaps.
The LUT works fine in photoshop…
I’ll experiment some more later and see if I can find out whats going on.
I’ve started recreating the curves manually in 3ds max… but its going to take quite some time… so I’m still open to suggestions.