Reviving an 11 year old thread. There might be others out there who are thinking of refreshing their door trims. My car’s previous owner glued faux leather and left unsightly residue. First try, the glue seeped through the cloth. Got me thinking how I can avoid it. Light bulb moment. The grove around the trim looks similar to the grove in sliding doors where you tuck the fly screen. Got the foam spline and spline roller from bunnings. Like what others have done, use the old trim as a stencil to cut your new trim. Lay it on your door trim. Tuck the section with out the grove. When your happy with the fitting, roll in the spline. It should push right in. If the spline doesn’t stay, you can use some pva glue. Quick job and the spline covers imperfections in the cut.
old door:
New trim: (Spline blends quite well)