Customize certain days/times for overtime

Could you please add the ability to make certain days and times different rates? For example, my work pays overtime Sat and Sun and Monday through Friday from 6pm to 10pm so if I could block those times off as overtime that would be great. A further complication is that the overtime is only shifts that start at 6 and end at 10, not the shifts that start at 4pm and end at 12am. So I don't want the 4 hours between 6 and 10 to count as overtime if the shift starts earlier than 6pm.

Thanks