ZXID distribution contains subdirectory called servlet. You should link this into webapps directory of Tomcat servlet container
cd ~/apache-tomcat-5.5.20/webapps ln -s ~/zxid-0.17/servlet zxidservlet
You also need to set allowLinking flag in apache-tomcat-5.5.20/conf/context.xml (the reloadable flag avoids having to restart Tomcat if you recompile the .class file):
<Context allowLinking="true" reloadable="true">...
The file servlet/WEB-INF/web.xml describes the example zxid application. The actual application lives in servlet/WEB-INF/classes which is actually just a symlink back to the top level of the ZXID distribution. Therefore the zxidhello.class file appears on the top level and the wrapper classes, which are scoped in zxidjava package, appear in zxidjava/ subdirectory. From the servlet container's perspective the directory appears to be apache-tomcat-5.5.20/webapps/zxidservlet/WEB-INF/classes/zxidjava
After make javazxid and restart of Tomcat (killall java; apache-tomcat-5.5.20/bin/startup.sh), you can access the application using URL (defined in servlet/WEB-INF/web.xml)
http://sp1.zxidsp.org:8080/zxidservlet/zxidHLO?o=E