Noticing that this is a rather old link, there is my own implementation of the EDLL in case you had not found it yet! 

This Enhanced DLLs page is the first I wrote before starting on the project for real.

This works great with MinGW and does not require to have all symbols defined in a tree like definition. (i.e. these DLLs can link back to the main executable, just like under Linux and many other Unices.)