How to treat exempt employees like non-exempt who must enter time?

Is there a good way to set up exempt associates as positive-pay time reporters and treat them like non-exempt employees who have to enter hours in time and labor to be paid? They should NOT automatically receive the standard 40 hours of work per week (all hours up to 40 -no overtime- would need to be entered on the time sheet or be unpaid). Thanks for the help. This is needed for government billing (using Payroll for NA).