Custom source to field in Feeds module? I'm setting up a way for a Drupal site to import data from third party sites using a PHP script that creates a XML structure.

I'm using the Feeds module, which otherwise works fine. But I miss something.

Now, I need to add a custom source from the feed that adds data to a field.

Like that I have a  inside the XML  that I want to be used for the nodes image_field. I need more then just a image, but as an example.

How do I do that?

Is there perhaps a way that will work so that I wont have to code it by myself?

PS. Since I've coded the script that creates the XML, I could easily change XML to about anything else that might work better. DS.
Feeds Xpath Parser module can help you map custom fields to your xml values.  I've used this myself.  There is also Querypath Parser which may do the same thing (I've never tried this one).