http://www.zuneboards.com/forums/zun...-znotes-d.html
This is the closest you can get at the moment.
You can insert .txt documents into the correct folder, add them to that folder, edit, delete, save, etc.. then just extract from the game, and edit again on the computer.
I have not tried this (Its possible to enter, but I am not entirely sure about extraction) and you can only use .txt files.