Is there a way to subclass a method programatically?

In particular, our framework has an OptionGroup class which in the base class has no options. This class has been dropped on many forms and set to various number of options. Now I want to do something in the keypress event which is only in options and not in the option group. Can anyone suggest a way to programatically override the keypress method of the options in the init method of the OptionGroup?

Any suggestions would be graciously attempted.

Thanks,
-Isaac