Need to pass Cookie header

Working on a project that needs to communicate with a backend that was originally built for AS2 a ways back. The backend is expecting me to pass the Cookie header in my POST. However, due to new security restrictions, URLRequestHeader will no longer allow me to set the Cookie header…

http://www.adobe.com/livedocs/flash/9.0/ActionScriptLangRefV3/flash/net/URLRequestHeader.html

Is there some way around this, or am I stuck?

Thanks -

Moge