My understanding (someone please correct me if I'm wrong) is that you must submit standardized test(s), preferably IQ and achievement. If only one of these is available because of financial or other considerations, you must submit the one test that is available plus a portfolio of work demonstrating exceptional ability.
Good luck with your advocacy. After investigating the dys application, I've decided not to apply for either of my kids. The school hasn't been receptive to changing anything given the qualifying scores themselves, and I suspect they've never heard of dys. Maybe for your DS, it will make the difference, and I can get some vicarious satisfaction - let us know what happens.
