Does this warning bother you?
You can get rid of it.
Open the Property window of the related EDMX file and notice that the Custom Tool property is set to "<RemoveToRestore>EntityModelCodeGenerator"
DevForce 6.0.1 puts this value there to (a) disable Entity Framework's own code generation and (b) make it easy for you to restore it later if you ever want to do so.
Let's say you don't.
Then just blank this property out ... and the warning goes away.
You can always restore it manually by entering the custom tool name of your choice (e.g., EntityModelCodeGenerator).
Do remember, however, that you can't have both EF and DevForce generating entity classes into the same project because you'll get pairs of classes with the same name.