Triggering workflow with System status activity change of CJ20N transaction

Hi ,

Can somebody kindly share some information with me on how to trigger a workflow when the System status of CJ20N transaction is changed?

I need to read the status before updating/save the activity through CJ20N.I have checked it STATUS_READ it's reading DB Current status.But i need to capture the change somewhere before its updated in the database.

Thanks,

Syam