The latest releases of Servletspy are available in a convenient binary distribution and also with complete source code from Sourceforge
You should consider to build Servletspy yourself. Get the source distribution. Servletspy uses Maven 2.x as build infrastructure. So make sure that the latest Maven distribution is available on your computer.
Before starting the build check and adjust the pom.xml descriptor of Servletspy to reflect your needs (e.g. change Servlet API version, Struts version...).
Please consult the Maven documentation in case you have further questions about the build process.
For developers who are helping to develop Servletspy or who just want the latest bits, the current development version is made available through Sourceforge CVS. Use at your own risk! Please check the Sourceforge pages for further details in respect of CVS access.