Most of the myth config (which one is the master backend/which ones are the slave backends, where to put the ringbuffers/recorded shows) should be automatically.
What the user is required to configure is the actual channel data/card data/ and the input to channel data connections. This is done by going into the Advanced Options screens on the OnScreen Orbiter ( the left bottom square with the pluto logo on it), clicking it and selecting the Setup MythTv option from there. The system should launch the mythtv-setup program on screen and give keyboard control to it. He can configure what it needs in there (the only "supported" channel data configuration is the DataDirect since that doesn't require manual input in the command line) and then exit hte setup. The system will then restart the local backend and start the mythfilldatabase program.
Since mythtv can't detect a new card until the master backend is restarted you will need to configure Myth on all MD's and then restart the whole pluto system. After that you should be able to click the TV button and be presented with the mythfronend app.
If something doesn't work like this please share it with us.