Update on my pose running technique!

I have been practising forefoot running for a couple of weeks now and it still doesn't come naturally!  I'm still unable to sustain it for the full duration of my longer runs as the top of my foot becomes very sore.  I'm sure this is just different muscles working and in time will adapt!  Unfortunately, I've been restricted to the amount of outdoor running I've been doing due to snow and ice, and have been staying safe on the treadmill.  However, once I get this technique perfected apparently ice will no longer be a problem to me!!  http://www.youtube.com/watch?v=S_pNb01YoSA