Have a look at Rob Conery’s TekPub ASP.Net MVC 2.0 Starter Site. He has setup DotNetOpenAuth as part of that. It should point you in the right direction
EDIT
My assumption was based on the the fact the OpenID and OAuth are the same. They are not the same but complimentary ideas. OpenId is about Authentication where as OAuth is about Authorization.
While not directly related to ASP.NET MVC the TweetSharp Library has an OAuth implementation written in C# that may be of some use.
TweetSharp OAuth workflow
Simple OAuth integration for Twitter in ASP.NET MVC
OAuth with Silverlight for Windows Phone 7