Hi,
you may customize pdfOut method in gridPdfWrapper.php like here:
public function pdfOut() {
$this->cb->setFooterMargin($this->minOffsetBottom);
// send PDF-file in browser
$pdf = $this->cb->Output('grid.pdf', 'S');
}
PDF is storing as string in $pdf variable. Now you may use any zip-maker for php.
There are a lot of php-classes which are used to zip data.