1. Go to http://subclipse.tigris.org/svnant.html and download the latest svnant-x.x.x.zip
2. Extract svnant.jar, svnClientAdaptor.jar, svnjavahl.jar and svnkit.jar from the zip file and put them into your classpath
3. Create a ant properties file that contains your svn classpath setting and put it at the same level as your build.xml. Below is an example where svnant jar files are located at lib folder.
4. Put the following at your build.xml