Hey friends.
So finally I tried installing HALanucher and also ATVLancher. Both are working when I open it. I've no idea how to set any of that as my default launcher. YouTube videos said that MiBox will ask to choose a launcher when I press home button. But I tried every button to get that pop up. No way. MiBox is not asking which launcher to choose.
Normally not possible as far as I know. There was a bug / issue / feature with nvidia shield was able to change the default launcher. Don't know if that is still the case.