Re: XB Coupe chrome door trim attachment
I bought a set of those clips and still wasn't sure, so I went to a panel shop and asked them. Long story short, they said if it's not a 100% restoration, just glue them on like all modern cars do with their trims. They said if I ever want to take them off again, open the door, roll down the window and drag piano wire or similar under the trim to cut the adhesive.
I eventually did stick them on with some adhesive being really careful so that you couldn't see the 'glue'. I filled the back of the trim in about 6 or 8 places, and then put in on the door with masking tape to hold it in place until it dried. From memory I used 'Parfix' brand that I bought at Bunnings which looked like black silicone.
They look great and have never come off, so it did the job for me.
I'm sorry that this doesn't help you with your problem though.
I've seen trims that 'push' on, meaning that you would place the plastic clips on the door pins and then press the chrome trim onto them. Other than that I could only suggest to ask a panel shop like I did.
If you do figure it out, perhaps post here so the next person with the same problem can find the answer.