The engine does get hot (especially the exhaust manifold) but the top of that cover doesn't get that hot, must be the plastic used and the insulation on the inside. The whole reason there's a cover is to prevent the heat from escaping the engine so it can warm up quicker on cold days... looking cool is just cosmetic.
I used simple aerosol Vinyl Dye, didn't bother sanding or anything just giving it a good clean, sprayed right over it, over where the silver was coming off and the black underneath was coming through and it came up good, though if you want a glossy finish do the usual preperation.
My wifes engine cover was painted by the previous owner in that high temp paint, it's got no where near as nice a finish as real paint or a dye... in fact it looks crap