I did this with the BMW shadowline stuff. Quite easy really. Just make sure you do it on a nice warm day and the stuff is easy to shape around the contours. I bought the 3" wide stuff, cut it in half, and used the sharp straight edge of the vinyl on the edges that are close to the paintwork (i.e. bottom edge of the window trims) so I didn't have to cut that edge, only the top edge. I hope you get what I mean.
There is no real need for a DIY, as everyone will have there own way of doing it. All I can say is take your time, and be prepared to do sections over and over to get it right.