Mine was easy.
There is the control box that I mounted on the firewall inside the car. Then there are sensors that you rooute to different places. One for each door that will tell the box if a door opens, and one for the hood. There was one for the trunk, but I don't have one, so I removed that one.
I had to drill 3 holes, one for each door and one for the hood. took me a good 3 hours, but only because I was being careful where I routed the wires, like behind pnls and under carpet, instead of just tucking them in.