PeopleSoft Payroll 9.2: Tennessee Garnishment Dependent Exemption Set-Up

Does anyone have advice for setting up a garnishment in Tennessee with the $2.50 per week dependent child exemption? Tennessee: "There shall be added as exempt to the judgment debtor the sum of two dollars and fifty cents ($2.50) per week for each dependent child under sixteen (16) years of age and a resident of this state". For example, for an employee paid bi-weekly the calculation is 25% disposable earnings, minus $5.00 per child. Is there a way to have the $5.00 deducted from the 25%? Currently, we allow the 25% to calculate on the paycheck, then