It is possible to connect, like described here: https://blog.consol.de/software-engineering/ibm-mq-jmstoolbox/

The main parts are:

SET AUTHREC OBJTYPE(QMGR) PRINCIPAL('admin') AUTHADD(DSP, CONNECT, INQ)
SET AUTHREC PROFILE('SYSTEM.ADMIN.COMMAND.QUEUE') OBJTYPE(QUEUE) PRINCIPAL('app') AUTHADD(DSP, PUT, INQ)
SET AUTHREC PROFILE('SYSTEM.DEFAULT.MODEL.QUEUE') OBJTYPE(QUEUE) PRINCIPAL('app') AUTHADD(DSP, GET)
SET AUTHREC OBJTYPE(QMGR) PRINCIPAL('app') AUTHADD(DSP)

* Create a queue
DEFINE QLOCAL('MY.QUEUE.1') REPLACE
* Authorize app user
SET AUTHREC PROFILE('MY.QUEUE.1') OBJTYPE(QUEUE) PRINCIPAL('app') AUTHADD(BROWSE, GET, PUT, INQ)

Then connect with JMSToolBox:

• If you want to connect using the app user you have to use the DEV.APP.SVRCONN channel

• If you want to connect using the admin user you have to use the DEV.ADMIN.SVRCONN channel