Chest roll to headstand help

Tried this one first time today and I was completely helpless. I don't think I lack the strength rather flexibility and timing. Are there any excercises to help develop this skill? Or any hints on what to think about etc, looks so easy and effortless in the gb dvd.

It took a little time to get this motion down. I did nothing more than to keep trying. It is certainly something that has to be felt, and once you get the feel, the movement can be better replicated. I am at the point that I can get to the handstand, but not consistently keeping form at the end. If there was anything I would emphasize, it would be having a nice arch, and just practice building momentum with the roll. Even now, I still give it a couple of rolls back in forth before I punch up.