Create a new browser bookmark, for example, in Chrome click the star icon at the right in the address bar, make sure the Folder is Bookmarks Bar, and then click the Edit... button:
In the edit box that opens paste the following code as the URL:
javascript:(function(){var root=(window.location.pathname+window.location.hash).replace(/.html.*$/,'').replace('cf#/','').replace('/crx/de/index.jsp#','').replace('siteadmin#/','').replace('/editor.html','');if(!document.forms.ta){document.body.insertAdjacentHTML('afterbegin','<form name="ta" target="_blank" action="/etc/replication/treeactivation.html" method="POST"><input type="hidden" name="_charset_" value="UTF-8"><input type="hidden" id="path" name="path" value="'+root+'"></form>');}document.forms.ta.submit();})()
Make sure the bookmarks bar is visible: Settings > Bookmarks > Show Bookmarks Bar (or Cmd+Shift+B / Ctr+Shift+B.
You can also call tree activation directly from the siteadmin while the required parent page is selected in the navigation tree, and the displayed URL is e.g. http://localhost:4502/siteadmin#/content/geometrixx-outdoors/en
PS: If you want to fix/update the bookmarklet code then paste it into the form at http://subsimple.com/bookmarklets/jsbuilder.htm and click Format.