OK, so the information is already in a session variable?
on the confirm page, locate the collowing lines of code:
$nextIndex = count($PP_PayPro_optional[0]);
$PP_PayPro_optional[0][$nextIndex] = "MERCHANT-SESSIONID";
$PP_PayPro_optional[1][$nextIndex] = "".session_id() ."";
and change that to:
$nextIndex = count($PP_PayPro_optional[0]);
$PP_PayPro_optional[0][$nextIndex] = "MERCHANT-SESSIONID";
$PP_PayPro_optional[1][$nextIndex] = "".session_id() ."";
$nextIndex = count($PP_PayPro_optional[0]);
$PP_PayPro_optional[0][$nextIndex] = "COMMENT1";
$PP_PayPro_optional[1][$nextIndex] = "".$_SESSION['comment1Session'] ."";
$nextIndex = count($PP_PayPro_optional[0]);
$PP_PayPro_optional[0][$nextIndex] = "COMMENT2";
$PP_PayPro_optional[1][$nextIndex] = "".$_SESSION['comment1Session'] ."";
you will need to modify this to use the names of the session variables you have created.