There are a lot of “CU” colleges. Which one are you referring to? Also, engineering is going to be a very, very tough major for a kid with a 22 ACT. Honestly, he needs a backup major in case that doesn’t work out, and whatever school he attends should offer that 2nd major. Can he live at home and go to any college (CU that you mentioned, for example)? That is the best way for him to keep costs down.
As an aside, is he getting accommodations now for his learning disabilities? If they are documented by a medical professional, he may be able to get extra time on the SAT or ACT, and bring up his scores.
Also, I don’t know if you’ve been looking at the other financial aid threads, but are a couple of links to look at. Note that some of these posts are a few years old, so look at the college websites to see what is available now. But you still might find some items of interest:
http://talk.collegeconfidential.com/financial-aid-scholarships/1359504-tuition-free-colleges.html