How to connect signal/slot in QItemEditorFactory?

How can I connect signals from editors registered by using QItemEditorFactory?

In the following coloreditorfactory example,

QItemEditorFactory *factory = new QItemEditorFactory;

QItemEditorCreatorBase *colorListCreator =
new QStandardItemEditorCreator<ColorListEditor>();

factory->registerEditor(QVariant::Color, colorListCreator);

QItemEditorFactory::setDefaultFactory(factory);

I want to connect currentIndexChanged signal from QComboBox which ColorListEditor is subclassed but don't know how. Any comment or advice will be greatly appreciated.