Is your son in public school? things change all the time with the college board, 3 years ago, most of the accommodation was handled through the guidance counselor AND the test had to be administered at your home school (regular accommodations like extra time were at any center that offers accommodation, but computer with specialized software was a home school thing).
If this is your case, I'd start with the school counselor -- does he have a 504? If so, can you call a meeting? It's about testing accommodations so it's reasonable to make it a formal meeting with notes taken and responsibilities doled out.
Why does he need equatio for SAT? Does he work out his problems with equatio? Or does he use it to make it legible for grading?
In which case he'd need it for AP, but not for SAT.
To get the specialized software, you will need a bit of testing to prove it-- more than our school offered. Our experience WITH all the testing was that college board didn't really have a grasp on disabilities and we needed to specifically ask for everything and then they turned it down or offered something silly that would be useless. And it took phone calls to explain. Phone call from school counselor to us so he'd know how to answer-- so you need a counselor who will work with you, or you need to convince the counselor to WANT to work with you (like have a formal 504 meeting).
And finally, check out the time it takes to use software. We could not get extra time AND software. Mine could not take the Calc AB test because approval did not come in the 7 weeks they said, and did not even come in 6 months! When the software didn't come through, DS worked with an awesome math teacher who thought DS could learn to write well enough. Then he asked for unlimited graded paper because the writing was huge and could never fit in their space. That got approved more easily. But first they gave the software with no extra time. Turned it down, and asked for extra GRADED (not scratch) paper instead.
I hope our story helps-- it is an old story and I'd like to think things are always improving. At that time, one of the considerations was student grades and if you got good grades, they were less likely to accommodate. If I remember, they were removing this in their considerations? AEH probably knows. But, start early and work harder than you think is necessary and be pleasantly surprised if it goes more smoothly.
