Just completed my install. Looks pretty nice, not a tremendous difference but it does class it up bit. Jut my 2 cents. It really was extremely easy to complete. Took about 35 minutes start to finish. I used the instructions from this link listed earlier in someone's post: How-To: Fog light HID kit in 2011 Jeep Grand Cherokee (pic heavy)
The only difference in the steps I took was rather than "cutting" off the pop rivets, I actually chose to drill them out. Used something like 1/8" drill bit took it in just a tad and then popped it right off. Rather then purchasing a "pop rivet gun" that I saw someone mention, I just went down to O'Reilly's and picked up some universal body trim inserts and they fit perfectly and look no different than the originals.
One tip if you choose to do this is in regards to the black trim around the wheel well. He mentions not pulling to hard because the trim is still attached, well if you can see the gray or green colored tab (see his image by the tape), you have already pulled to hard. I should have taken a picture, but in order to release that clip without breaking the point where it attaches to the black trim, reach up behind the felt liner with your hand and some pliers and gently squeeze the clip from the back side and it will pop out without the potential of damaging your trim. Once you get to this point, you will likely see what I am talking about. (perhaps I was just unlucky, but I consider myself very meticulous so if others have popped that clip out by simply pulling on the trim... kudos to you)
We have another WK2 that I have purchased the grill for so perhaps I can get some photos next time around. Best wishes to all who take on this simple upgrade.