Well it's a bit late, but then I don't stop by here very often. But then you have waited 20 years, to wait another month shouldn't hurt very much.
I found this 2009 conversation stream with a picture
By that I assume you mean this thread.
What is shown in the picture is what is known as a full extension drawer guide. Means the draw will pull out the full distance of the drawer.
The above guide looks like a Accuride drawer guide but I can't be sure. Pretty sure that there is a release mechanism but can't remember just how it functions.
There are three parts to the guide. The part attached to the cabinet, the part attached attached to the drawer and the movable part between them.
See the hole in end of the movable part, the release is probably in there.
If you can find the brand of the drawer guide you may be able to get more information about it. The manufacturer of the desk did not make the drawer guide. Look for brand of guide.
See this web site for Accuride disconnect instructions.
http://www.accuride.com/Woodworking/...Disconnect.asp