Not sure this will directly answer your question.... however this will help the real issue I think you are getting at. And that is Air Consumption right? You want to be able to consume less air, thus allowing yourself to stay down longer. We all want that!

I think the best thing to focus on would be your recovery time. This is what alot of great runners work at. How long does it take you to recover from a jog? As you continue to focus on your cardiovascular health, your ablity to put your body though the stress of running jogging, and diving will improve. I hope I'm making sense. The bottom line is... if you want to increase your "lung capacity" what you need to focus on is your cardio workouts, your body will adjust, and you will end up using less air.
Resdivemedic what do you think?