I have not heard of any such wrapper or instrument. But I am puzzled by why you would like to directly expose the created EMF classes as a web service. Wouldn't you get a web services API that is too thin to be practical?
Going back to the world before EMF, one of the (right) criticisms in the OMG MOF 1.x specifications was that mapping MOFs to CORBA IDLs gave interfaces that required too many requests. But in defense of MOF 1.x, the CORBA IDL did not get value type support until CORBA 2.3, after the MOF 1.x design was frozen.
People have lost interest in using IDL after MOF 1.x. By the time the MOF guys started working on JMI, the preferred approach was to move the models as XMI drops and use the fine-grained APIs only for in-memory deserialization. And this is what JMI supports, and basically how EMF works. (But with EMF, you can also implement model persistence using other technologies, for example, using Teneo.)