PHP and ComboBox AS2.0

Hi,
I have searched far and wide on google and various forums and can not come up with a solid answer. I have a contact form that I am modifying into a questionnaire form using Input text boxes and PHP. My PHP is simple, it consists of

<?php
$sendTo = "myemail@myemail.com,";
$subject = "NewForm";

$headers = "From: " . $_POST["firstName"] ." ". $_POST["lastname"] . "<" . $_POST["email"] .">
";

$headers .= "Reply-To: " . $_POST["email"] . "
";

$headers .= "Return-path: " . $_POST["email"];

$email0 = $_POST["email"];
$message0 = $_POST["CompAddy"];
$message1 = $_POST["city"];
$message2 = $_POST["state"];

$name0 = $_POST["CompanyName"];

$message="Name: $name0

";
$message.="Company Address: $message0
";
$message.="City: $message1
";
$message.="State: $message2
";


mail($sendTo, $subject, $message, $headers);
mail($email0, $subject, $message, $headers);

?>

and my actionscript is simple as well because its just a button that collects the Vars

on (release) {
    form.loadVariables("email.php", "POST");
}

How would I implement this using a combo box (I know how to set one up but how do I send some Vars over to the PHP script.)

Thanks in Advance,
neonreel