Using RIA's AuthenticationService with Windows Authentication

I have a Silverlight 4 application that uses RIA services and Windows Authentication. I am trying to make it so that if authentication fails the user gets redirected to a login page. I cannot get the login page to authenticate the user's username and password because "Windows authentication does not support lo开发者_StackOverflowgging in."

Does anyone know how to authenticate a user's windows account via a custom login page using RIA services and the Authentication Service?

Thanks in advance!

Excuse my bad english.

Well, i had the same problem, but i looked this video and find one way to implement a windows authentication login with Silverlight 4.

http://channel9.msdn.com/Shows/SilverlightTV/Silverlight-TV-44-Top-Four-Questions-from-the-WCF-RIA-Services-Forum

In the minute 12:20 begin the rock and roll! ;)