Entity Framework itself is provider-based, and is designed to operate over a relational database. If you really wanted to, you could write your own provider for EF that reads from/writes to an xml file, but it would be a huge amount of work.
I expect you should really be looking at one of:
- LINQ-to-XML
- XML (de)serialization
- XPath/XQuery
- XSLT
Entity Framework doesn’t have a natural fit in this scenario.