Here's a quick step by step with a couple of pics. Unfortunately, it was pretty dark when I got home so I can't take pictures of the inside until tomorrow. I'll have to explain the best I can.
First, you'll need a couple of flat head screw drivers, one pretty short.
Open up the hood and remove these round pieces using your flat-head. Gently pull up on the black plastic and you will hear a few pops and feel the bumper come loose at the top.
The grill inserts are three pieces with the largest in the center. Look at your replacement pieces and you will see how they connect. There are small tabs (with a lip) that holds them in place. You will need to use the small flat head to allow the lip to release.
Start with the center of the grill insert and while placing the screw driver in the spot where the current tab is held, put weight from the outside. If you get it right, the grill will come loose very easily. Find each of these starting at the top and working your way down. Sometimes, I would place one screw driver between the piece that holds the grill in place while prying gently with the other. This is by far the hardest step but if you pay attention and use a flash light to see what I'm talking about, you'll get it.
When putting on the new pieces, start at the ends and work backward. I found it easier to stick my arm through the open space of the center grill to put weight into the new tabs. You want to make sure each "snaps" into place.
Here's the after pic of my Limited:
Again, I'll take more pictures in the near future. If you take your time and don't just force it, you can make it work.