Default how do i make 4 on screen buttons on my N5?

Hello i wanted to kno how to make it so i have 4 on screen buttons on my N5? i want to have back button.. home button.. menu button.. and recent apps button.. im sure there are roms with it but is there like a mob i can use.. because im on cataclsym rom which is the BEST rom i have ever flashed on this phone.. so i do not want to switch really.. if there is not any mods and i have to flash a diff rom.. what rom is close to cataclysm? i do not like CM based roms.. thanks!!!