I would like to use the same functionality of addChildViewController, but for the version 4.3 (addChildViewController is only available in version 5). Thanks in advance.
Although it's not recommended, you can create an instance of a UIViewController access it's view property and set it as a subview of the main view your main UIViewController is managing. It works, and I never experienced a problem with this.
That said, the recommended way is to have a NSObject subclass to act as your sub-controller, and not use a UIViewController as it has special behavior.