Hi,
Now I understand your question. Maybe your postings doesn't has a zero balance. But I think the LSMW can't does this residual item. You have to verify this.
I think by BDC is more easy to do that. Also, you can try to do LSMW in the visible mode and post a document and at the time the SAP askes if it is to create or not a residual item, you can click "yes".
Check this information: Requirements for Using Payment Advice Notes - Payment Advice Notes - SAP Library
JPA