hmmmm. i have coated over anodized AL, many times, with excellent results, however e-coating is not nearly the same thing. since e-coating involves the application of a lacquer &/or paint to the substrate, albeit far thinner than a conventionally applied lacquer, I would say that the powder would have a difficult time adhering & flowing properly, but apparently it can be done.
I found this excerpt from an article on this topic. "A Wisconsin light-fixture maker, Ruud Lighting in Racine, Wis., finds that an acrylic powder topcoat over an epoxy e-coat base is an ideal finish for its products: Powder provides the UV protection the corrosion-fighting e-coat can't."
let us know how they come out.