Mod for Jelly Bean Nav bar on Kit Kat Tablet?
For continuity across all Android device sizes, from phones to tablets, the Android team completely removed the old tablet layout from 4.4 going forward. It is no longer there so it isn't something that can just be switched on. 

It would have to be built back into the ROM, so you may ask your ROM developer or look to see if a ROM has already done this.