There is no drilling needed. You do need the plastic trims that go around where the seatbelts are mounted.
I used to sit in these seats when I was young and my kids love sitting in them now. Whilst the position is far from ideal in a rear end situation if you look at almost all MPV's etc the rearmost seats are right at the back and no crumple zone for protection.
Nice little read on crumple zones
https://en.wikipedia.org/wiki/Crumple_zone