You could create multiple weekly schedules (check Mon-Fri but not Sat or Sun), one schedule for each half hour.
For example: Weekly (check Mon-Fri) at 8:00 AM. This would run each weekday at 8:00 AM, one time. Then create another weekly schedule (again, check Mon-Fri) at 8:30 AM and so on until you have scheduled every 1/2 hour through the end of your business day.
It's cumbersome, but that is the only solution I have been able to think of so far using only CE/BOE.
Alternatively, you could schedule your report to run on an event (such as a file event) and depend on some other application with more scheduling options to delete/replace a file to trigger the event.