I just patched the deleted KNG Slow Motion mod.
This not the Critical Slow Motion mod.
With this mod you can activate Slow Motion at the press of a button
Installation:
1. download mod
2. extract content to \yourWitcher3Directory\mods
3. Edit the input.settings file (located in Documents\The Witcher 3) to let it work.
in every state you want it to work (e.g. Exploration, Horse, Combat), place this line (change the key with whatever you like)
IK_Mouse4=(Action=BulletCam)
and set the file to read-only
4. done
Uninstallation:
1. delete \yourWitcher3Directory\modKNGSlowMotion
2. done
Settings:
1. open \yourWitcher3Directory\mods\modKNGSlowMotion\content\scripts\local\kngslowmocam.ws
2. change line 12: SlowMoFactor = 0.2f to your liking.