How to add custom plugin controls to CkEditor
In ckeditor.config.js you need something like this:

CKEDITOR.editorConfig = function(config) {
  config.extraPlugins = 'vicheck';
  CKEDITOR.plugins.addExternal('vicheck', '/sites/all/plugins/ckeditor/vicheck/');
  config.toolbar_DrupalBasic = [ [ 'Bold', 'Italic', '-', 'vicheck' ] ];
}


where vicheck is a plugin.

This works for me using an old CKEditor module. I don't know if the latest versions have any change.