The problem you are having is probably because you are trying to use the wrong version of the plugin.xml file for your version of Eclipse. Struts Console has two versions of the plugin.xml file: 1 for Eclipse 3 and later and one for earlier versions of Eclipse. The help instructions on my website explain how to change the plugin.xml file for your version.
Note: You will probably have to delete the ".metadata" directory in your workspace folder before changing the plugin.xml file. This is because Eclipse caches plugin.xml files and will not pickup the new one.
If you continue to have problems, feel free to email me directly.