Reading Data from a Cookie

My company uses a cookie to transfer campaign codes. It does not use a query string.  Eloqua support advises that Eloqua cannot receive such information from a cookie, at least out-of-the-box. I am looking for anyone  that has been able to develop a method that Eloqua can use to pass a campaign ID from the cookie into a hidden field on a form. I would love to know how it was done.