Customization of "PO Requisition Account Generator" workflow.

Hi,

I need to customize "PO Requisition Account Generator" workflow.

I have to populate company and location segments of "Charge Account" based on the PO requisition requestor's expense account.
"Charge Account" is specific to a distribution line.

For every PO requisition line, there can be multiple distribution lines.
How do I identify which PO requisition distribution line is being processed by the workflow?
Is there any attribute that stores the unique identifier of the distribution line?

Thank you in advance.

Thanks & Best Regards,
Krishna