These topics discuss how to extend the functionality of the Cart Product Feed plugin using “Custom Modifiers”. To make use of this, you will need an understanding of PHP.
Custom Modifiers can add and remove attributes on the fly. They can change the contents of the attributes or even reformat the feed output. They exist as outside plugins, meaning that even if you upgrade Cart Product Feed, your custom modifier code will be preserved.
Feel free to download the sample custom modifiers and rework them to suit your needs.