Replication Server 15.2 includes the set template to option for the create error class command.
create error class error_class [set template to template_error_class]
create error class my_error_class set template to rs_oracle_error_class
Use create error class, and set template to, and another error class as a template, to create your own error classes. create error class copies the error actions from the template error class to the new error class. See the Replication Server Reference Manual.