Non-standard pay periods

Management would like to implement a 'flex time' schedule (start at 7am and get every other Friday off). They asked me figure out how to do this in Vantage (8.03.408b). To avoid the overtime issue, we need the new pay period to start at noon on Friday (this is ok in Michigan). Salary is no problem, but I can't figure out how to get the Friday afternoon Time clock entry for the hourly employees on to the next pay period. (We are using the Vantage payroll module.) Any ideas?