modify scope_condition in a model using acts_as_list

Does anyone know how to modify the generated scope_condition method
that acts_as_list generates?

I need to change that method at different times during program
execution, but have been unable to do so.

Well, I realized how to do this, and it was a little obvious.

I simply copied the source of what acts_as_list does and changed the
class_eval method call to instance_eval (and removing everything

instance_eval scope_condition_method