Lately I needed to transfer messages from OSB to BPM Suite. The setup was that OSB calls a Webservice implemented by a Mediator component that publishes the message on a JMS queue. The webservice request contains a mesage header and a message payload. The payload published as the JMS message-content, but the message header elements were added as custom JMS-properties to the message. How to do that is quite easy and described for instance in this blog.
The JMS Adapter forJMS documentation can be found here, and the particular part about the properties here.
In essence, in the Assign Values part of the Mediator configuration, custom JMS-properties can be referrered to as

$in.property.jca.jms.JMSProperty.custompropertyname

The BPM Process listens to the queue and needed to be adapted to read the JMS-properties. I could not find info about that, but it turns out to be simple: in the ServiceCall activity you have the Service Properties link:
 This will bring up the service properties dialog:
The green-plus and pensil icons can be used to add and edit the service property assignments:

The property name is of the same structure as with the mediator: 'jca.jms.JMSProperty.name'.
The expression must denote an automatically instantiated dataobject of type string. I tried to use a structured business object, but then apparently only the root element is instantiated. On run-time I got errors that the assignment of the JMS-property to the particular element failed. So for each JMS-Property I created a separate Dataobject of type string. And that works perfectly.