"setProperty()" can be done from Qt Forms in QtCreator?

"setProperty()" can be done from Qt Forms in QtCreator?

I'm trying to understand the example of using the customized class
QLedIndicator, found here. There in the ui_mainwindow.h file I found the
following lines of codes:
ledIndicator_0->setEnabled(true);
ledIndicator_0->setChecked(false);
ledIndicator_0->setOnColor1(QColor(255, 0, 0));
ledIndicator_0->setOnColor2(QColor(176, 0, 2));
ledIndicator_0->setOffColor1(QColor(28, 0, 0));
ledIndicator_0->setOffColor2(QColor(156, 0, 2));
Normally in Qt Creator the lines of codes in ui_***.h file is written
automatically with the changes made in the forms, but I can't see how I
can enable these lines of codes from the forms. Could you please explain?
Thanks.