I\'ve been trying to automate a log in to a website I frequent, www.bungie.net. The site is associated with Microsoft and Xbox Live, and as such makes uses of the Windows Live I
I'm not sure if you're still working on this or not but the Windows Live Development site has a lot of info on it to help with using the Live ID API. I've not had much of a dig into it but their Getting Started page has a load of info plus a link to download sample applications detailing how to use the service in a variety of languages (including C#).
You can download the sample application from there.
It sounds pretty interesting what you're trying to do, so much so that I quite fancy having a play with this myself!