If you take the SAT through a talent search, you can fill out their talent search ID form instead of using a photo ID. However, I would recommend that your student bring a photo ID anyhow to avoid unnecessary explanation/hold-up on test day.
Prepare your child to locate the correct information board, get in the correct lines, and go to his testing room all by himself as parents are not allowed in the building in most normal administrations. I have heard that sometimes the proctors are more lax in special administrations.
Prepare your child to either write in cursive or fake it as he will be asked to copy a statement in cursive.
Prepare your child for questions from other testers as he may be the only obvious young kid there.
I'm a little fuzzy on how it all worked at our school for the 7th grade ACT, but our school did let parents in the building to wait before the test started (but not in the classrooms or during test, just in the lobby/commons area). Most of the HS kids were alone, of course, but they weren't made to be, which was nice. YMMV depending on school. (Then again, knowing the school, maybe they weren't supposed to allow that...)
I
think we got a form from the talent search for identification that had to be signed once at home and once again in the test room. There was something to copy but cursive wasn't required for the ACT verification statement.
The other thing you might want to do is make sure they know where the bathrooms are.
