I am trying to visualize this...
What part?
Clean around your door opening good and wipe it down with Vaseline. Maybe tape off the outline of the door so that you can pull tape up and have a nice neat gasket that removes any squeeze out
Clean your door good and put a bead of red high temp silicone on it around the mating surface.
Put the door in place and close it.8
Pull the tape away that removes the squeeze out
Let dry
You should end up with a perfect gasket adhered to the door but not to the Vaseline coated shell. Clean the Vaseline up.