CKEDITOR.plugins.add('fancyimage', {
    requires: ['fancydialog'],
    init: function(editor) {
        editor.addCommand('upload', new CKEDITOR.dialogCommand('upload'));
        editor.ui.addButton('fancyimage', {
            label: 'Добавить фотки',
            command: 'upload',
            icon: this.path + 'images/button.jpg'
        });

        CKEDITOR.dialog.add('upload', this.path + 'dialogs/upload.js' );
    }
});