How add plugins to Pidgin Portable

It works the same as locally, just that you use PidginPortable\App\Pidgin in place of %PROGRAMFILES%\Pidgin and PidginPortable\Data\settings\.purple in place of %APPDATA%\.purple in the instructions for installing the plugin. Note that most plugins are very poorly documented. Some require one or the other location. Some will only work with specific versions of Pidgin.