I need to pay sick leave at an average hourly rate determined over the past 90 days.

With the new California sick leave law/rule, we need to pay sick leave for hourly employees at an average hourly rate calculated over the past 90 days. This could swamp our payroll technicians if they have to make that calculation manually. Is there anyway to do it in the system. I guess I'm hoping for something like the average cost in the Distribution system.