How do I export a GWT project into a executable JAR file with Eclipse?

There's a huge legacy codebase that I'm working with and I need to export it into an executable JAR file to make it easier for my co-workers to run it. It's a web application built on top of GWT, but I'm not sure what kind of application server it uses (e.g. Apache Tomcat, Eclipse tells me it uses a "built-in" server).

The run configuration shows up when I try to run the project, but not when I'm trying to export it as an executable JAR. All it does is run an application server on the machine, and allows a user to access it via 127.0.0.1:8888 in a web browser. Any ideas?