Monitoring Sharepoint Sites with Nagios

Hi,

We have various sites published via Sharepoint proxied via ISA Server 2006, we also utilise the following forms of authentication to these sites.

Windows Authentication (windows pop up)
Windows Forms Based Authentication
Sharepoint Forms based authentication

Some sites are https some are http

All sites are published from one box utilising host headers and Sharepoint utilises a form of url transformation so I am having trouble getting nagios to check the availability of the sites without getting warnings about unauthorised access. Has anybody come up with a command or a usage for check_http that can parse usernames and passwords or basically just do what I want it to do.

Cheers

GD