Quote:
Tweak that makes select sign button not only select, but also instantly cast the selected sign.

do through script, no ini edit need ...

Similar mod:
http://www.nexusmods.com/witcher3/mods/81/?

Better solution - patch input.settings without editing + possibility redefine keys here + alternative sign casting:
http://www.nexusmods.com/witcher3/mods/865/?