The idea is to pull out the data you want as meta data. There is no way to specify tokenisation based on mimetype to tokenise xml with a specific lucene tokeniser.
Create your own aspect to hold the extracted meta data in properties. Use XPATH expressions to map xml elements to these properties. You could use one hold all property or several, it depends on what you want to do. The properties are likely to be of type d:text.
You can not extract metadata into properties of type d:content.