In case if we have a PDC system and the confirmation is done from te PDC system then the below is one approach which uses most of the standard features of SAP
1) The data from the PDC system can be passed to the SAP and placed in a application server dedicated location / folder.
2) Whenever the file is placed an event can be triggered to get a job started .
3) This job needs to have a customized program to trigger an IDOC. You can use the IDOC method PPCC2PRETTICKET to process this data and generate an IDOC
4) Once the Idoc is placed it will be processed immediately, configure the message type accordingly in the partner profile
4) This message type will not post the confirmation, we have to again run the CORUPROC1 program, which will help to post the goods movements.
5) In case of the post processing use the CO16N - Confirmations to reprocess the error things.
This is a high level plan this has to be coupled with event to automatic triggering of the jobs and other process.
The sequence of activities is to be given more care.