There's two ways you can do it. You can take the easy route which is to take the grill, trim the bottom and use some means to fasten the lower section (ie. zip straps). The top will fasten just as the original did.
The more extensive route would be to replace the header panel, lights, grille and front bumper with the 06' style, which is also possible.
If your just going for a new look, I suggest the first route. It's a lot cheaper and easier. If you have a ranchhand style bumper you may not even have to trim it (I didn't have to), stock bumpers you will have to though.