lucy24 - 12:14 am on Mar 12, 2013 (gmt 0)
If the pages are already gone, nobody will ever see the header. It's like the server saying "The page you requested isn't here, but if it were here, this is the header you would get." You might be able to rig some kind of jiggery-pokery using a php script, but not in Apache alone.
I think what you really want to do is remove them via gwt. I guess the FilesMatch problem applies here too, unless all the defunct files live in the same directories.
Come to think of it, how are you identifying the pages so they can return that 410 in the first place? Unlike 404, a 410 doesn't happen on its own; you have to take some intentional action.
Can't help suspecting that when you say "410 pages" you really mean "404 pages that were intentionally removed". And that's a whole nother question.