A few batters before your rookie is up, try to get base hits with 
them. For example, use Carl Crawford, Hank Blaylock, and Justin 
Morneau. If you want to do this, load up the bases if possible. Once 
they are loaded you should be able to hit a home run with your 
rookie without problems. If you do this four times you will receive 
unlimited Power Blasts for the rest of the game.