Is it possible to add buttons for example?
No
Or change settings in the Tone mapping area via maxscript?
Yes, you can access all VFB settings as renderer properties, all "colorMap_*" properties (tone mapping+LUT), "bloomGlare_*" for B&G. Those for sharpening/blurring are less consistent in naming unfortunately, and there are all "curves_*" ones.
I tried hard to understand your issue and went through the other thread as well but failed.
What is exactly the problem to load a *.conf file into the camera(s) before starting to batch/render them? Or to load a conf file into the VFB to quickly switch the settings? Ok, I see at least two things to improve right now if I would like to achieve a quick change:
1. The VFB or the CoronaCamera, they do not remember any paths at all (yes, this is very bad and annoying when working in a project based structure). If so, it would be at least only click + double click to load a conf from a directory (instead of one click or scroll if it would be a list or button like in your mockup). This has to be improved by the Corona team, alternatively we could get a function in the maxscript interface to load *.conf files into VFB.
2. There could be finally that "Throw current VFB postprocessing settings into selected/active CoronaCamera" option. But this could be quite easily scripted (button/hotkey) with the exception of curves, because CoronaCameras don't have them :)
Would those changes/improvements go in the desired direction?
Good Luck