Watch the Approach 2: Breakdown online guitar lesson by Vicki Genfan from Rhythm Makeover: Vicki Genfan
It might be nice to just start playing the chords alone at first - without the pinky hammer ons. This will give you a chance to focus on getting that light, bouncy feel going. The key here is the left hand - pulsing or releasing the pressure on the strings. This is such a great technique to learn and master - do yourself a favor and take the time to get it down!