The easiest way right now would probably be to add a couple new alert macros. For example, if you added
$config[‘alert’][‘macros’][‘rule’][‘8_to_5’] = ‘HOUR(NOW()) BETWEEN 8 AND 16’;
$config[‘alert’][‘macros’][‘rule’][‘Mon_to_Fri’] = ‘DAYOFWEEK(NOW()) BETWEEN 2 AND 6’;
…to your config.php file you should get macros.8_to_5 and macros.Mon_to_Fri as options in alert builder. If you include them as AND conditions and set them to equals Yes the alert should only fire when the normal conditions are true plus the current time is between 08:00:00 and 16:59:59 and the day of week is between Mon and Fri.