Hi Drew
I'm doing custom trims - just going to put a polished alloy strip top and bottom of the trim, not doing the oval shape in the middle. Does your signwriter have a scanner? If so get him to scan the chrome shape and then have it computer cut from the foil. It will follow the contours ok and will only need tweaking to fit smoothly around the bends. I guess it will depend on how smooth the chrome section is as to how the finish will look, maybe lots of careful sanding might be involved if the surface is broken. If the trim is just faded then it should go a lot easier.
I can get my mate to use his computer cutter to do the same in the alloy composite he has to get the same shape if I decide to go that way. They have a very thin and very sticky clear doublesided tape they put on the back so it wont come off in a hurry. The alloy RS badges are stuck onto the car with this stuff.
There are also guys who do plastic chroming but getting the strips off the trim and refitting would be a nightmare. It took a lot of care and effort just to strip off the old vinyl of the trims I am refurbishing. I presume you want to over the chrome strips without disturbing them. Cheers, Len