Installation:
Extract all the files inside the Install folder to your GTA IV main folder, then go to the Shaders folder and extract the shaders folder inside one of the archives to your common folder in your GTA IV main folder - C:/Program Files/Rockstar Games/Grand Theft Auto IV

Credits:
Fabriciuz, DKT70, AzR_MaNiiAkixS & Andrej Dudenhefner.