As Kedhar implied, if the information is on IT0015, then it will be processed during Payroll Calculation, through function P0015. In table view V_512W_D, modify the parameters of WT 9BLE (and other similar WTs) so that they could be saved in RT, and make the appropriate changes to your PCRs so that these WTs are read from IT0015 and transfered into RT without any changes to them, except perhaps moving the value from the NUM field into the AMT field (if required).
Then it'll be easy to add that WT into the Remuneration Statement (PaySlip).