In order to use WindowTester with your product, you should be able to launch your product in eclipse - using the eclipse run configuration.
If your product is an RCP application, follow the directions athttp://downloads.instantiations.com/Win ... p_app.html
to import the application into eclipse.
If your app is a java app, create a java project in eclipse, then add all the application jars to its path. Then in the run configuration specify the location for the main method.
Once you are able to launch your application in eclipse, then you can use WindowTester to record GUI interactions.