To make any serious change, patch or enhancement to XDoclet we recommend you download latest code from CVS.
By default the source code, template files and samples are all included in distribution, but we strongly recommend you to download latest source code with complete build scripts from XDoclet's CVS, so that you have access to latest code and all the automated jobs the build script does for you. Follow the instruction explained here.
Also it's recommended that you subscribe to xdoclet-devel or xdoclet-user mailing list where those who wrote XDoclet can help/guide you.