you can do it with regular gloss but it can get a bit smelly when you turn the radiator on! If you are painting them white then it will yellow fairly quickly .. mind you that has never stopped me ... I can never be bothered with buying radiator paint!
always use satinwood in the same colour as the walls. Don't understand the obsession with white radiators (unless of course your walls are pale), or now I come to think of it the need for radiators to be shiny. Hair yes, radiators no.