If you copy mfejblib.jar to a different directory, you need to change the classpath in the manifest.mf file in the EJB's .jar file, which is in \myservice\myservice.deploy (Windows) or myservice/Repos/myservice.deploy (UNIX).
For most application servers, you can do this using their administrative tools. Alternatively, you can use a jar command similar to the following:
jar -uvf myApplication .ear mfejblib.jar