My son also has an ADHD diagnosis (combined type) and I too had no idea what to ask for. The school had some ideas which they've implemented:

- shorter assignments
- frequent breaks
- desk position (at the side of the class so he can get up and move around without disrupting others)
- seating close to a reliable "buddy" student who can prompt him to resume work when needed

Oh, just looked at the clock. Speaking of DS, I need to get his breakfast started, but I'll come back later with more...