On the taskbar, click Start, point to Administrative Tools, and then click Server Manager.
In the Server Manager hierarchy pane, expand Roles, and then click Web Server (IIS).
In the Web Server (IIS) pane, scroll to the Role Services section, and then click Add Role Services. On the Select Role Services page of the Add Role Services Wizard, expand Common HTTP Features, select WebDAV Publishing, and then click Next. On the Confirm Installation Selections page, click Install. On the Results page, click Close.
Enabling WebDAV (After installation of the tridion content manager)
In IIS Manager, in the Connections pane, expand the Sites node in the tree, then click the SDL Tridion 2009 Web Site, select the virtual directory webdav, double-click the WebDAV Authoring Rules feature. When the WebDAV Authoring Rules page is displayed, click the Enable WebDAV task in the Actions page. Once WebDAV has been enabled, click the Add Authoring Rule task in the Actions pane. When the Add Authoring Rule dialog appears: Click All content to specify that the rule applies to all content types. Choose "All users" Select Read, Source, and Write for the permissions. When you have completed these items, click OK. For a detailed description go to: http://learn.iis.net/page.aspx/350/installing-and-configuring-webdav-on-iis-7/