default_scope and scoped_methods in 2.2.2 ?

I am running rails 2.2.2 and cannot upgrade to 2.3 at this time.

However, I would like to use a default_scope and so I have installed
the default_scope plugin.
This works great for standard AR classes but does not carry through
Single Table Inheritance without adding the default_scope declaration
to every class. Not very DRY

I was hoping someone could shed some light on the following
undocumented ActiveRecord method.

def scoped_methods #:nodoc:
   Thread.current[:"#{self}_scoped_methods"] ||= []
end

I am hoping I can make the following change without breaking anything.

def scoped_methods #:nodoc:
      Thread.current[:"#{self.base_class}_scoped_methods"] ||= []
end