ValveSource XSI plugin help

When I try to install the plugin it just doesn’t appear at all in the browser, maybe I’m putting in the wrong folder? It seems to be looking in a non-existent folder ‘Softimage_Mod_Tool_7.5/Addons’.

here mate http://usa.autodesk.com/adsk/servlet/item?siteID=123112&id=13525256&linkID=12544121