Unfortunately it's not an ANT+ profile it is Shimano specific. I would also like to look at interfacing with it but I have not managed to get a contact with anyone at Shimano that can help. It's a bit frustrating.
Afaik the new Garmin edge 1000 can pick up that info, so they should be in contact with Shimano.
Don't know if Garmin will be helpful, but maybe they can help to get into contact with Shimano.
As I understand it, the D-Fly sends the information to Garmin Edge 1000 (and SCIO) using ANT+ protocol. I imagine then, that this should have an ANT+ device profile?