Adding hours to OT-in-lieu

Is it possible to add hours to a time off option? Ie if an employee has accrued 15 hours of OT-in-Lieu, his/her manager has just approved an additional 15 hours to be added to the "bank". It would be great to have an option of going in the back end and "adding" the 15 hours to it.  Please note that I do not use the time-sheet method.