-download the mod version which suits you (difficulty level).-open mod archive "flash mod x.0x.rar"-unpack the content of "all_in_one" folder (content of this folder, not this folder) to your game's directory "/the witcher/data/"
-overwrite files if needed (replacing game files is completely safe and wont break anything)if you want to install only few changes from the mod, not whole mod, unpack content of folder containing feature you are insterested to "the witcher/data/" folder.