Kumar,
ejb-jar.xml is a standard file. You can create it my hand easily if you aren't using an
IDE.
The other files are optional IBM specific files. You can create them through the admin console of WebSphere after you've deployed. At least the first time. After that, you have the files and can include them yourself. They are used for things like binding resources to the JNDI.
IBM does provide an Ant task, but I don't think it generates the files. (Where would it get the information.) Also, you have to be running on a box with WebSphere installed to run parts of the Ant tasks.