Editing Spool

hi,

After a spool is created , how can it be edited ?

Requirement :

SAP standard report is executed and a spool is created for generating a PDF . The new requirement is that , page numbers needs to be shown on the PDF , ie it needs to be there in spool.

How can we edit a spool and insert page numbers ?

or

Can we get the spool into an internal table and insert one line in each page and create a new spool? If yes, How?

Thanks,

Paul.