R12.2.4 - Oracle Projects Integration with Payroll

We are on R12.2.4 and have Oracle Project Costing and OTL implemented. We have a 3rd party payroll system. We want to able to integrate 3rd party payroll with projects to cost based on actual cost rather than the standard cost. What table and columns does the 3rd party payroll need to populated before the PRC: Process Payroll Actuals program is run. Also we need to how the Pay Element Distribution Rules table need to set up. We don't understand a lot of columns like Distribution Basis and Time Card Pay Element. Are there any other setups to be done