FYI, you have an error around line 20, it should be
if ((int)MODULE_PAYMENT_AUTHORIZENET_CC_AIM_ORDER_STATUS_ID > 0) {
$this->order_status = MODULE_PAYMENT_AUTHORIZENET_CC_AIM_ORDER_STATUS_ID;
}
Here is what needs to be in the stock authorizenet_cc_aim module
function process_button() {
// Hidden fields on the checkout confirmation page
$process_button_string = tep_draw_hidden_field('cc_expires_month', $_POST['cc_expires_month']) .
tep_draw_hidden_field('cc_expires_year', $_POST['cc_expires_year'], -2) .
tep_draw_hidden_field('cc_number_nh-dns', $this->cc_number_nh-dns) .
tep_draw_hidden_field('cc_cvc_nh-dns', $_POST['cc_cvc_nh-dns']);
return $process_button_string;
}















