There is a couple threads on them on here, but they are right by saying to drilling. Install is not bad, just time consuming. Take your time. It took me and my wife 2:45 to install the front 2 fender flares, and just 2 hours for me alone to do the back ones.
Cutting the inner fender flares is the worse part of the install. The fronts are more difficult to do than the back ones. Just take your time and you will be happy with the results.