If you know xdoclete you can use xdoclet to have the portlet.xml generated for you.
However to write jboss specific descriptors you need to do them by hand. However you can use an XML editor like the free XMLSpy home edition.
thanks for your answer. Can i use IBM Websphere studio too ? If yes, can i deploy my portlets (compatibly)? Do you have experience with them ?
I don't have any experience with WS, but if you don't tie in to any of IBM's proprietary crap, you should be fine with standard portlet development.