maxConnections and connectionConcurrency only affect the number of connections available for MDB delivery, and unless you have a large number of MDBs and/or are connecting to a number of different queue managers the default values should be ok for most configurations. Connections for outbound JMS are configured separately.
If you can raise a PMR then I can put in a change to allow these values to be overridden using Java system properties. That would be a better solution long-term than unpacking/repacking the .rar file.