JMS does not support editing messages in place, you have to copy the message and resubmit as a new message.
Hermes does not support graphically editing messages - its been on my todo list for some time - however you could save them as XML and then edit the XML before resending them.
Select your message(s) and "save as XML". Edit the XML in place - it should be fairly obvious whats going on - and then File -> Open Messages or click in the toolbar. Once you've opened the file you can drag and drop the messages onto a queue or topic.