Hi Nick,
In the end I bought some double sided tape and placed this on the inside of the trim, and then managed to hook the trim back into place with the help of the tape. It's been over a year and they have not come off once, although they do not look as flush as they once were. Lesson learned here! If you're thinking about wrapping the chrome, I'd advise leaving the trim on the car and wrapping them this way, or paying a body shop to do this for you.