How to create a reuse timer overlay for the hotbars?

[Landiin]

Played with this idea just a tad today before raids and I don't think it can be done. The only DD I can see that might could be used is DynamicData.SpellInfo.Bank_X.Key_X.ReuseSec but u can't use that in a ProgBar because there is no way to reliably set the Max value.

I love the idea and have wanted what Dolby posted for some time now. Maybe someone will have more time to work with it then I and figure something out.