After downloading the mod, use a program such as 7zip or WinRAR to extract the main folder of the mod.
Drop that main folder of the mod to assets/mod_overrides. The assets folder is supposed to be in your game's installation folder (don't know where that is? click here). Create the folder if necessary
Extract into mod_overrides.
Weaponlib: Extract into mods.
CAFCW: Extract into mod_overrides.
Tacticool Packs: Highly recommended for the true Capitalism AR15 derivative experience.
Tacticool Charging Handles: Generic AR15 charging support for the Gen 1 MCX is not accurate to the real weapon, but I'm not going to bother deleting support out of support for people who do like the customization option.