Ensemble doesn't seem to be able to process ISO-8583 messages natively, so I tested it with an open source Java parser via JavaGateway. I parsed the message in Java, converted it to a pipe delimited string then passed it into Ensemble. That's about it.

I got the Java parser code here: https://github.com/vikrantlabde/iso8583-Java/blob/master/src/ISO/iso8583.java

Anthony