Oh. I got it.
Thanks.
Posting what I did for future reference.
Placed
Utils_RecordBrowserCommon::register_processing_callback('custom_pre_register',array('Custom_PreRegisterCommon','add_action_bar')
in the module install.
Then added the function to the Custom_PreRegisterCommon class:
public static function add_action_bar($values,$mode){
switch ($mode) {
case 'view':
Base_ActionBarCommon::add(
'clone',
'Register',
Base_BoxCommon::main_module_instance()->create_callback_href(array('Custom_PreRegisterCommon', 'register')));
break;
}
}
Thanks again for the advice.