You could have a s simple point on the API that could be called by
either containers or user's application.
If the user is running a simple SE environment, he could simulate the
container by directly bootstraping the message-consumers beans.
If he has an injection framework on the client (aka container) the
container can then do the job for the injection.
something on the API such as
WhateverClass.bootstrapConsumer(messageConsumer); (or whatever other
method name you choose)