Very easy, only 2 things to be really careful with are:
1. don't bend / flex the headliner too much as they can crack.
2. Watch the clips around the sunglass holder and interior light as they can snap easy. More so in these extreme conditions so leave the heating on in the car for 15mins of full blow
Start from the back with the visable pop clips and work forward is what I do. Any free advice needed call me pm'd you my bat phone number