I doubt about it too. You may want to check it with Booksmart studio. They sell prinatble metal sheets and in their studio they use several differnt printers including Z3100. If it is possible to do so, they will know about it.
I'm also interested in this. I've already bought the metal sheet sample pack (before I'd decided on the Z3100).
I spoke with Kory at Booksmart Studio, and he told me he thought it would work OK but hadn't tried it. He said that he had it on his to-do list, and thought he'd have a chance to get to it next week. He took my email address and promised to email me with the results. I told him about this thread, so I wouldn't be surprised if he followed up here as well.