Herculiner Bedliner project question for those who used it?

I have a 92 full size ford Bronco. In 2 weex i am spraying herucliner on the whole outside of it with a gun. Looking at some of the body work done on the pictures of herculiners website i must say im impressed. I am thinking about doing the inside floor part down the line. Is that done by roll on or spray on. Prep wise what did you do other then ripping up the carpet interior or stripping it to the floor base or is that all just needs to be done? I am only doing the floor inside if i decide to do it. Did you roll in on or spray it on? thanx...