Drag and drop the "Colt Model 1911" folder into your lml folder. 

To merge this portion of the mod with any other mod that uses the file "weapon_pistol_m1899.ymt" just open the file with notepad and use the search "<UnlockWeaponHash>". Once you've found it just replace the text that is between "<UnlockWeaponHash> </UnlockWeaponHash>" with "WEAPON_REVOLVER_CATTLEMAN". After doing this it should look like "<UnlockWeaponHash>WEAPON_REVOLVER_CATTLEMAN</UnlockWeaponHash>" but without the quotations of course.