Sandcastle that is. Here’s a 26 page article on doing just that…

The most effective way to document .NET code so that others can understand it and use it, is to use XML Documentation and Sandcastle. It isn't that easy. Michael Sirens produces the easy guide to the process that Microsoft never managed, and introduces several applications that help. ContentsXML Documentation Comments: First Look. Doc-Comment Elements. Automate Your Doc-Comment Creation. Level 1