using group widget with json instead of xml

Hi there.. new to xataface and I am so far... impressed. I would like to adjust one thing though. I use a fair bit of JSON encoded fields to store meta data and it would be very helpful if I could get xataface to read and write JSON data behind the group widget instead of xml. Is there a pluggable system for parsers? is there anyway I could customize this without tearing the entire app apart?