After downloading the mod, use a program such as 7zip or WinRAR to extract the main folder of the mod.
Move the 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 for PAYDAY2 folder). Create the folder if necessary
With SuperBLT & Beardlib installed in your Payday 2 files, which everyone does lets be real who doesnt, place both files in the .rar labeled "HA, you know it!" into the Mod_Overrides folder & blammo the mod is installed. Simple as can be