While you can brush paint MM Metalizers, they are only effective on large areas if airbrushed. A better alternative, if you are not into the airbrush thing, is to apply one of the art wax treatments such as Rub 'n Buff. Depending on how carefully you are with the application and buffing procedure, you can achieve some amazingly realistic metallic finishes.
Just be sure to mask surrounding areas, because these wax treatments can get really messy before they set.
Phil