Hmm, I'm not sure it will work with this MDF piece. You should remove the old inner plastic thing, you don't need it. On the door there are four holes for screws, see if you can drill holes in the MDF to match those on the door. I doubt it but give it a try. Or maybe drill new holes in the door to match the MDF. Here's how it looks on mine, but my MDF is specifically for my car.