JBoss ESB exception handling

Issue

I need to expose on our ESB an Web Service Request/Response sync and internally I need to consume some external services via actions (web service client action, custom actions, etc).

My question is how catch exceptions and build an custom message as output to my Web Service Request/Response.

Now I use exceptionMethod property on my custom actions but this way is not valid for my service because I need to build a custom message as output to my clients then I don't know how to do this.