Entity framework: Access / modify the Command Tree or otherwise provide custom mapping C# functions

Question

Hello,

I'm investigating a method of providing transparent bi-temporal versioning of entities with Entity framework 3.5 or 4.0. What I want to do: When an entity is saved, the former entity has to be copied into a separate table, for example, if the entity is Customer, it will be saved in Customer_AUD. Upon retrieval, based on date/version and relationship policy, the "head" revision of the instance will be retrieved or a former version. What I don't know how to do:

Either provide a custom mapping function written in C# or find a way to generate stored procedures for the operations and map to them.

Could anyone please give me an idea of how to do the above? Any help will be apreciated.

Best regards, Simon.