If you have somewhere under cover, you could paint them on the car.
Preparation has to be given a bit more time though, as the areas will need masking off to prevent overspray.
Then a few sheets of newspaper to mask off the larger areas.
Followed by a light key of the plastic trim.
Then a wipe over with a dry, lint-free cloth.
Painting-wise, you will need a few (3-4) light coats of Tough Black - remember the amount of paint applied to the surface varies with the speed you move the areosol & how close its held to the surface - be consistent with the coats.
It will appear glossy (at first), but as it dries, it will become either the satin or matt finish - depending on which one you have chosen.
Do all trims (one coat per pass), and work your way around the car then leave it for around 30 mins to check for a consistent finish - wait a further couple of hours before carefully de-masking.
Et voila, the perfect way to miss the Royal Wedding!