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
Install like a normal Mod_overrides mod, because it is one. Do note that this mod also includes a menu track of krump kings' lightnin, which is the song used in the original windows xp gangster edition song. This song will not be added if you do not have beardlib installed, but it shouldn't cause any problems otherwise.