Tcpdf Example 003 : custom Header and Footer

Hello,
I need to customize the header of a pdf generated with the tcpdf library in a blank application.
I managed to do this by editing the tcpdf.php file in C: \ Program Files \ NetMake \ v9-php73 \ wwwroot \ scriptcase \ prod \ third \ tcpdf \ and everything works.
Wanting to leave the tcpdf file unmodified, I saw example 003 which allows you to customize the header function with:
// Include the main TCPDF library (search for installation path).
require_once (‘tcpdf_include.php’);
// Extend the TCPDF class to create custom Header and Footer
class MYPDF extends TCPDF {

How can you create it in scriptcase?

Thanks