I think now you have to type:
`rewrite create-config <TAB>`
But that's all it does - it just sets up the dependencies and helps you create a barebones config. Then you need to add the rules like Join() and such yourself using the ConfigurationBuilder.addRule() methods.
I hope this is at least a little helpful!
Also, if you are using Forge 1.1.12 and up, you'll be notified of what new commands are available after you install the plugin (I think.)