I was trying to figure out how to do this... I wanted a hot-folder setup that I could just drop files into, and have DNG Converter chunk away in the background. Ben Long has an Automator Action set up, but it took a while for me (not too familiar with Automator) to figure our how to make it work. Using that, and making an Automator "application", you can just drop stuff on the application icon and it runs the process.
I've posted an explanation here: