Add data in Raw Data & Advanced tabs in FileInfo panel

I think you need the XMP toolkit to work with that. I'm pretty sure you can alter those fields but I've never done it. I think you use AIDocumentSuite::GetDocumentXAP() and then use the XMP SDK to parse & alter it. Then you use AIDocumentSuite::SetDocumentXAP() to write it back to the document. I don't know how to use or install the XMP SDK, but presumably you can find information here:

http://www.adobe.com/devnet/xmp.html