How to install:
Put the cloaking.cs file in the CLEO folder.

How to use:
Press and hold the crouch button. A smoke will puff out and you'll be in thermal vision meaning you're now in cloaking mode.

Your weapon will automatically be switched to knife. You can use other weapons while in cloaking mode, but it's more fun to use the knife and do the back stabbing technique while cloaking.

Cloaking mode will be deactivated if you stand or attack.
Just be in crouching stance while in cloaking mode so that everybody can't see you.

Side effect:
When you get out of cloaking mode, some enemies seemed to get hypnotized by the smoke puffing and can't move till you hit them.