You need access to the starter motor which means working underneath the car , so safety first. The job itself is not difficult and the instructions are quite clear so it should take about an hour , once you have access.
I got a set last month. Having jacked the car up to get to the starter motor, my face was so close to what I was doing I couldn't focus, and I got a local garage to do it for me. It seems a very straightforward task but its difficult without a pit or a ramp.