Would have to be sprayed (There is a thread with this on somewhere) ....... As from what i remember power coating is done when they warm the object up in an over and then dip the hot item into an airated bin of coloured polymer crystals (plasitc coat finish) or special paint pigments which stick to the item it is then baked on a lower temp a bit more to ensure it is fuly coated evenly then bought out to cool so I guess if they tried that the engine cover would be deformed and poss melt dependign on the plastic is made out of.
As for makign it all fit snugly and making your bay look tidy again thats a good job jobbed and nicely done fella.