Found a way to get punt returns...
 

Ok this isnt the most realistic way, but it sorta solves the problem.

To do this, you must have the CPU punt length slider from 15-17.

Then when the CPU chooses to punt, just select the punt block play.

Teh CPU will audible to protect the block which will give you a few seconds to return a punt. The thing that sucks though is that you have no blockers, but then again, when you do an original punt return play, the blockers dont block anyway!