There should be a hook available. First you need to find the template that is being called. Look under development - admin templates. I'm on my phone so I can't give you the exact name but there is most likely a hook in there.
As for the db field it is recommended to prefix your field as to avoid conflict. Then as Jeremy said, you'll have to extend the data writer the same way you did the controller or model (I forget which but I remember you doing it from one of your posts).