CFBundleDocumentTypes and iPad Camera Connection Kit (SD Reader)

I am trying to register a custom document type in the iPad app, hoping that I will be prompted to work with files on the SD card attached to the iPad via the camera connection kit.

Does anyone know if this is currently possible (or even for sure if it is not possible)? I was hoping that the Camera tab in Photos would use the document interaction controller for types it didn't understand, but it looks like photos don't check the alternative handlers at all - I also tried to register support for the jpg type, but was not requested. when using photos and loading JPG images from SD card.

There is an SD reader application called Zoomit that appears to read many different types from an SD card:

http://currentphotographer.com/zoomit-application-enabled-sd-card-reader-for-the-iphone/

But it looks like it has something to do with custom hardware which is different from the standard SD reader.