Create an 'Add to favourites' link

To create an 'Add to favourites' link:

Select some text in the editor.
Click the 'Make a link' button.
Leave the buttons set to 'a page on another website'.
Copy/paste the following code into the box:

javascript:window.external.AddFavorite(location.href,document.title)
Be sure to set the page title by right-clicking the page in the left panel. The page title is used as the text for the entry in the visitor's favourites - so be sure that it makes sense out of context.
This will work in Internet Explorer, it may not work in other browsers.