the about-page of wso2ei 6.1.1 (https://docs.wso2.com/display/EI611/About+this+Release) mentioned the possibility to develop and especially to deploy msf4j apps in wso2ei:
From WSO2 EI 6.1.0 onwards, it does not ship the functionalities of WSO2 Application Server (AS). However, you can develop applications using MSF4J, JAX-RS or JAX-WS technologies and deploy in WSO2 EI. If you already have applications in WAR or AAR formats, use WSO2 AS 5.3.0 or Tomcat as the server to deploy web apps. Nevertheless, WSO2 still provides complete development and production support for WSO2 AS.
I am very interested to do this, but unfortunally I can not find any information on this topic. I would be happy to receive information and links to this topic.