I had to do the same thing the other day. Like was said above, there are like 2 screw clips in the front wheel well (they are made out of plastic and if they're like mine might not unscrew correctly). I can't remember if there were any in the back, but the rest is held on by the clips like are in doors. I broke some of them and while they aren't the same, I bought some replacement ones at AutoZone. I think they were for a Honda/Nissan. The only thing that I had to do was modify the part where they slide into the skirt because the original ones are square on the bottom and the ones I got were round. I just had to cut a little bit off of one side to make them square and it fits just fine.
BTW, they make a tool to get clips out and sell it at most part stores. They're made out of metal usually so you want to be careful so you don't scratch paint, or wrap the tool in electrical tape or something so it doesn't scratch anything.
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