I was recently asked to put together a live demonstration for a customer on how they could use SPNEGO to access their web based Domino applications. To do that I opted to build a lab environment consisting of a Windows domain controller, a Windows based Domino server and a Windows 7 workstation so I could have a clean environment to present with.
Here is a modified copy of that presentation which will hopefully help you configure SPNEGO in your own environment.
Thank you to Sean Cull at Focul for clearing this presentation so I could share it.
If enough people are interested I would consider doing a webcast of this with a demo against my lab environment.