In order to find your language support plugin, KDE needs a .desktop file with some meta information.
X-KDE-Library=...this must be the same as the name of your library, i.e. look into the
kde4_add_pluginline and use the same name
X-KDE-PluginInfo-Name=...this must be the same as the name of your plugin in the code, i.e. look into your main plugin .cpp file and find the
K_EXPORT_PLUGINline, more exactly the first argument to the
After installing your plugin, make sure to run
kbuildsycoca4. For testing, try duchainify or ktraderclient.