How can I include the licence number of a customer in a ZIP file?

Hello,

I have a PHP program, constituted from many files.

What I want is:

Include the licence number in the top of each PHP file (As vBulletin 3) and output the whole program to the user as a ZIP file.

How can I do that?

Thank you...

i'm using a command line tool and exec() for creating zip files. there is no other way as far as i know.
if there is one, let me know :-)