Not responsible for bricked phones.
This is a mod how to enable navigation bar(on screen buttons) , its very simple and easy...
Add the following line at the end of buid.prop file
now on reboot we will have nav-bar like on nexus 4
To disable hardware keys, I used root explorer go to system/usr/keylayout click and hold on kaypad.nl and choose from menu open in text editor and 139,158,172 edit the home to hom and do the same on all 3 lines and hit save and reboot,
Plus I went and deleted all the 139, 158, 172 lines from external_kbd.kl, Generic.kl, MHLRCP.kl, osp3-input.kl and qwerty.kl. I dont know if that helps because I deleted them first then edited the lines in kaypad.nl.
Sent from my LG-E970 using xda premium