Currently, there is no way to control RW Photos from command line. Both the application and the documentation are incomplete. Though adding a command line support is not difficult and will most probably be implemented in the final version with an interface like this:
RWPhotos.exe your_command.rwbatchop image_to_process1.jpg folder_to_process ...
In any case thanks for the question, it is the purpose of the public beta to find the most useful functions that are missing.