An example of configuring routes that aren't defined in the 'routes' file. I don't know it this is the expected way to do this.
There is a ticket for this feature - which has been resolved - but no explanation as how one does it.
Ticket is here: https://play.lighthouseapp.com/projects/82401/tickets/12
Also stack overflow here: http://stackoverflow.com/questions/10116286/programatically-adding-a-route-in-play2-0
The other downside of this approach is that its configured in the app, so a plugin/module can't contribute routes without a little bit of fiddling with the main app.
git clone git@github.com:edeustace/play-injected-routes-example.git
cd play-injected-routes-example
play run
curl http://localhost:9000/injectedRoute //returns a string
curl http://localhost:9000/injectedRouteWithParam/2 //return 'the number is:
2'