Pass The Zip Code Value From The Script Into An ASP Variable, Such As A Cookie Or Session Object?

I'm using a geolocator service to find the zipcode of a web page visitor using the code below. This will be used to serve up ads to the visitor based on their zip code. The question is, how do I pass the zip code value from the script into an ASP variable, such as a cookie or session object?

<script language="JavaScript" src="http://www.iplocationtools.com/iplocationtools.js?key=my_site_key"></script>
<script language="JavaScript">
<!--[code].....