The provided link is for Outlook 2007 and and not Entourage. Entourage is Microsoft's mail client for Macintosh computers.

What can be done beside making client rule, you can easily create a folder on your desktop and simply click and drag any message to it. This is how you auto archive with entourage.

If you are looking to transfer these messages to a text format you can simply click on the message, located in the folder, and click on More info. Once you have the More Info screen open you can change the extension to .txt.

Hope this information was found helpful.