Whenever you get hit, there's a small window of time (usually just a few frames) during which both characters are "frozen" in their animations. To DI, you must hold a direction during this window of time. With normal DI, you can just hold the control stick prior to getting hit, but with CCDI, you have to let yourself get hit in the crouching position, and then smash the control stick in another direction during that window of time which comes directly after getting hit.
Try it with strong, strong attacks first... like Ganon's utilt.
ritt.no-ip.com - roy is top tier. (no, not really, you dolt.)