CAUTION: This post is not sanctioned by High End Systems, and could result in mysterious people following me around at night. (They would of course be somewhat recognizable due to the small flying pig orbiting a strange yellow planet on their shirt pocket.)
Just like stealing a car, this method is neither highly encouraged nor advisable.
Of course I didn't end up in this industry by paying much heed to authority OR instruction manuals, so here we go.
When I recently got my hands on a Catalyst V3 running on a G4 processor, I was told (somewhat emphatically) that it only had one output. I said, "Cool man, I can dig it", and promptly broke the rules. Upon checking out the video card on the back of the unit, I noticed something that is not un-common to video cards these days...a DVI video connection. Of course, not having anything that accepted DVI handy, I quickly absconded with one of those handy little DVI->VGA dongles that seem to come with most Macs nowadays.
Now when I plugged in the dongle and connected it to a projector, I pretty much figured the worst case scenario was that it wouldn't work. I guessed that my even-odds bet was that it would display the exact same thing as the standard VGA output of the video card. When OS X did its fancy screen dissolve and gave me a double wide desktop, I pretty much assumed that there was no way this had worked. So I started up the Catalyst software and, with many a pretty aerial effect in my head, turned the second output to full screen. I was floored to find that I had just hotwired the 'Single Output Server' to have a second output. After scrounging up a couple of extra 'boardroom' projectors and pointing them over the audience's heads, I was well on my way to a killer light show.
It's worth noting that you need to be very aware of what you are running on all layers at any given time, especially on a G4. By running dual outputs you are much more likely to be using movies on multiple layers which can severely reduce the performance of the server.
