To embed any external page into an iMIS site, you can use an <iframe> like this:
1. Go to Content designer, Manage content and create a new content record.
2. Select add content and place a single Content Html iPart on it (from the Content folder).
3. Show the source by clicking the tab and type in an iframe tag, such as this:
<iframe width="100%" height="652" frameborder="0" src="http://docs.imis.com/"></iframe>
4. Go to Tools > Site designer > Manage sitemaps and create a new navigation item that points to the new content record.
5. If appropriate, restrict the navigation item's Access Settings, such as to Authenticated User Full Control.