I don't know of any automated tool that will help you make a conversion. The good thing is that many different gateway configurations are pretty reusable (JMS, ftp, wsdl, etc) with very minimal effort, so hopefully your conversion won't be too tough.
I would definitely take a look at the JBoss ESB quickstart examples for ideas on how things work in JBoss ESB / how things might convert over.
Thank you very much Tom, Yes I know that there are lot of gateways available. But It is time consume to learn esb docs to change into ESB.