All scripts presented on this page require CLEO library. CLEO 2.0 for GTA3 and VC, CLEO 4 for GTA SA and the latest version of CLEO for Android.
CLEO for GTA3 / VC / SA | CLEO Android
Besides that, for most PC scripts, GInput is required:
So, even if you don’t have a gamepad, you need to install GInput anyway to use these scripts.
To install scripts simple put .cs file in CLEO folder. If there's a zip archive on release page, then the script requires additional files, copy the content of that archive to GTA root directory.
Downloads are available on releases page.
Alternatively you can find a list of compiled scripts on AppVeyor.
Visit CLEO topic on gtaforums.com to report bugs or suggestions.