Apple - Keyboard shortcut for launching Apps in Dock
Just downloaded a 99 cent app from the mac app store called "Snap" that fixes this. Now I hit command-1 and the first app in my dock launches. Awesome!
As @Am1rr3zA said, you can use the default Control + fn + F3. You can then press Enter or Space to launch an app.
You can change the key binding in the Keyboard shortcuts menu in the Settings application.
I don't know the exact solution but you can use control+fn+F3 after that you can navigate through Dock with keyboard arrow keys (→ or ←) and press enter on your desire app.