I also loved my DCTV. Only drawback of course was that the output was composite. It would be great to hack one into s-video or RGB. I may be interested in buying another one... I don't know what I'd use it for, but I always thought it would have been cool to write a DCTV workbench monitor driver and display 24bit workbench..
But to answer the original question, you can't use it as a composite out for normal use. You need an A520 adapter.
Now, a better solution though is to get the neobitz board and convert RGB->s-video. It's $30 in kit form.