Remember that you need to register the tool in the web.config file like this
<telerik>
<tools>
<add type="Telerik.Cms.Tools.SiteExporter, Telerik.Cms"/>
<add type="SEVDNUG.Web.Sitefinity.Tools.DataImporter.ImportData, SEVDNUG.Web.Sitefinity.Tools" />
</tools>
</telerik>
Extract the zip file to ~/Sitefinity/Admin/ControlTemplates/Tools