Its not easy at all. First you would need to remove about 7 or 8 clips, and to do that you need the hands of an 8 year old to fit in there. Then using two flat head screw drivers pry open one clip, while pushing out the grille.
Then the horsey is held in place by these locking washer things, so you would need to cut the posts off the back of the horse, thus making it useless for future applications except display on your desk.
I like ShowGT's suggestion of just having it painted right on your car. It's not impossible to swap it out, but it will take some work and if youre patient enough you can do it.