Exchange Server 2010 OWA SSO for Intranet User

We are using ISA 2006 publishing OWA to internet users  and we only use Basic Authentication on OWA virtual directory according to this article (http://technet.microsoft.com/en-us/library/ee921443.aspx).  Now we would like to implement OWA SSO for intranet users. Is it possible to enable  both Basic Authentication and Integrated Windows Authentication on OWA virtual directory ? So we do OWA SSO for intranet users and meanwhile keep the form-based authentication  for internet users?

Thanks in Advance.

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