Fshguy's guide is good, but I thought I'd add an extra tip for those who, like me, struggled with this achievement. Over much trial and error I learned that if you start an Iron Storm with the special hole and quit immediately, when you start the level again you will automatically start with most of the balls of an Iron Storm, but the best thing is that you won't use one of your balls when you start like you normally do, so extra ball! Another cool thing is that you can do this with all of the stages so start Iron Storm on the first one, quit out, then start Iron Storm on the second one, and so on. When you progress to the stage you will start with an Iron Storm, which to me is probably one of the best power ups.
Fshguy's solution says you start a special multiball if you lock two balls quickly. I believe this is a typo. What you actually want to do is lock all the balls to start the multiball, then immediately lose those balls until you hear a particular sound. This multiball probably has about 3 times the balls of Iron Storm. Another good thing is that you can start this special multiball and quit out and have it start the next time you play the table just like Iron Storm. I was only able to get this special multiabll to work on the Gamma and Epsilon tables (I think those were the ones, correct me if I'm wrong), but it's well worth doing those instead.
Hope this helps, and good luck.