I cannot think of any way to call CORBA as you would normally do a Java callout for Java actions. Creating a web service for the CORBA program, and then invoking it from your business service seems to be the way to go.
Here's an article that might be of interest to you. - http://www.oracle.com/technetwork/middleware/ias/how-to-ws-corba-089854.html
However, I would love to learn if you indeed can call a CORBA program without using web services. Do update this thread with your solution.