My daughter has both juvenile arthritis and Crohn's. She had a 504 in high school that listed accommodations for both conditions. When she decided which college she wanted to attend, we emailed the office of disabilities at her school and made an appt.
She met with the director of the office of disabilities and they talked about the accommodations she needed and how they'd be implemented in college. For example, she will take tests in the office of disabilities instead of with her class since she gets bathroom breaks, use of a computer for typing etc. We had all the documentation from her various doctors ready when we went to meet them and that helped set things up quickly and smoothly. Some of the other accommodations are extra time for assignments, extra absences for doctor's appts, special food (bland food - grilled chicken, pasta) made by the dining hall when she is flaring, moving exams by a day or two if she has a bad night.
Your best bet is to have him reach out to the office of disabilities or whatever the equivalent is at his school. Every school has a slightly different procedure.
I have no idea about funding college through a disability since we didn't do that.
Good luck!