Leveraging BIG-IP APM for seamless client NTLM Authentication

Hi, I have a problem using this with our Sharepoint. In the step "External Logon Page - iRule" (The External Logon Page Object), I need to dynamically set the URI (FQDN of APM Virtual Server) as the Sharepoint uses different URLs. Two questions: - How can I set an URI like http:\\$hostname\nltm\auth instead of a complete http:\\fixed.url\nltm\auth - Is there a chance for the NTLM authentication with different URLs? Is there a specific APM cookie that is set and its value could be replaced by the IP address or another value to be recognised by F5. I am asking because when using a different URL to the same APM virtual server, the NTLM authentication begins again (also an alternative Logon Page, if the NTLM authentication was not succesful) Thanks for your feedback!