Clean the specific dash areas that are to be covered by the trim thoroughly with isopropyl alcohol. The surface area should be free of lint, dirt and oil and more specifically, silicone-based "vinyl treatment products".
Vehicles that have been treated with vinyl treatments need to be thoroughly cleaned until the surface area is free of contaminants.
To test that the surface is free of contaminants, use a piece of masking tape and apply it to any of the cleaned surfaces. Remove the tape slowly. If there is little or no resistance, re-clean the surface and re-test with masking tape until the tape comes off with resistance.
Wipe with a clean damp cloth.