The recent retiring of the old msdn.microsoft.com (which allowed us to retire "msdn2" as a domain name) brought lots of challenges, not the least of which was pruning out a lot of old, unused content to help improve discovery of newer content. Once in a while, we discover something that should've been kept.
The good news for you is that it does look like your immediate question was answered in the wiki http://msdn.microsoft.com/en-us/library/ms537834(VS.85).aspx
"The HTML Editor sample can still be found in the Microsoft Platform SDK for Windows Server 2003 R2 and in the default install location,the folder location is C:\Program Files\Microsoft Platform SDK for Windows Server 2003 R2\Samples\Web\ie6\htmleditor.
Hope this helps."
Chris Slemp, Evangelist, MSDN and TechNet