The SAP Event Management procurement visibility process (PCM10) calls for a payment to be created against the PO using transaction F110. The SAP EM Application Interface is typically called using a BAdI but this time a BTE is used to trigger the SAP EM Application Integration. You'll find the code for BPT ESC_FI_CLEARING in the function module /SAPTRX/PAYMENT_SAVE_BTE_1040 for event 1040 (reversal) and application PI-EM. Use /SAPTRX/PAYMENT_SAVE_BTE_1030 and event 1030 for the payment itself. Use t-code FIBF -> Seetings -> P/S Modules -> Of an SAP Application to review BTEs.