Weekly time entry that crosses a month end...

We are trying to figure out the best way to have employees enter their project related time the last week of each month when the end of the month is mid week.  We are looking for a way to control what they can go back and update in that week.
Ex.  November month end is Wed. Nov 30th.  Time cards for that week will show Nov 28th thru Dec 4.

We require all employees to have their time in on Wed.   They could submit their time cards on Wed.  Then go in and reopen them to enter time for the rest of the week.  We can't allow them to update the time entered for November as we have already closed the period.