How much does a good score on ACT/SAT increase my chances whereas I can waive them?

What you need to do is contact each and every college in which you are interested and explain your situation. Some might (and I emphasize might) have a workable suggestion for you. However, you are just as likely to receive a response such as:

http://admission.universityofcalifornia.edu/freshman/requirements/examination-requirement/index.html

If there are no colleges which require SAT scores offer a workable solution, then your other opportunity, as @Lindagaf suggested, is to look for test-optional colleges.