When adding a plugin the code typically looks like this if you are trying to associate a button with the plugin .
where 'pluginFolderName' is the name of the folder you're using in the /plugins directory that contains a plugin.js file with all your methods.
Question : Can you add a plugin that is not in the /plugins directory ? Say you had another directory called /alt where you stored additional plugins (/alt/a /alt/b /alt/c ). How would the above code change to accommodate that ?
editorInstance.addCommand('mycommandName', CKEDITOR.plugins.pluginFolderName.commands.pluginmethod);
editorInstance.ui.addButton('mybutton', {
label: 'Button Label',
command: 'mycommandName'
});
where 'pluginFolderName' is the name of the folder you're using in the /plugins directory that contains a plugin.js file with all your methods.
Question : Can you add a plugin that is not in the /plugins directory ? Say you had another directory called /alt where you stored additional plugins (/alt/a /alt/b /alt/c ). How would the above code change to accommodate that ?

Re: External Plugin ?
CKEDITOR.plugins.addExternal("mypluginname","/.../plugins/mypluginname/","plugin.js");Where the file plugin.js contains a plugin definition like
(function() { // ... see the original CKeditor plugins })();That just works for me.