The following works for me where I wanted to provide the option of either paying via bank or paypal.
PHP Code:
if (isset($_POST['submit2']))
{
$params = array(
"submit_button" => "submit2",
"next_page" => "success_bank.php",
"form_data" => $_POST,
"finalize" => true
);
}
else
{
$params = array(
"submit_button" => "submit",
"next_page" => "paypal_submit.php",
"form_data" => $_POST,
);
}