Irule to authenticate with HTTP Proxy-Authorization field

Hi, I have to integrate a secondary proxy for streaming traffic in an existing infrastructure where there is already a squid proxy installed. My idea is to create a vip listening on the streaming protocols ports, balancing on a pool which members are the secondary proxy servers. Considering users with active sessions on the existing proxy, the client asked me if F5 LTM can authenticate them to the secondary proxy using an Irule that read info from HTTP Proxy-Authorization field, is it possible? The existing proxy uses NTLMv1 authentication method.