As my colleague Peter pointed out, you do this in the same
manner you would a normal topic. So this begs the question as to
why I felt the need to post.
Here's the deal. Personally, I avoid doing anything inside
the little area offered by the DHTML editor. I prefer to construct
things directly inside the topic in the area that will be visible
after your user clicks the DHTML link. Once I'm satisfied with
things, I then select it and cut it to the Windows Clipboard. then
edit the DHTML and paste the contents there.