That site uses an iframe which is an inline frame. You would create a seperate page with the text you wanted in the scrollable area and then add that to the main page in an iframe like this
<iframe src="text.html" frameborder="0" width="246" height="318" scrolling="auto">
Place text in here for browsers that do not support the iframe tag
</iframe>
See
http://www.cs.tut.fi/~jkorpela/html/iframe.html
for more information on iframes