I run it on 6 1600x1200 monitors. Over the last couple years, I've changed my monitor configuration from 4 monitors to as many as 8. The 8 monitor setup had 2 in portrait on either side of the 2x3 array. To the point, I've always had the Kelly-software matrix screensaver installed. But reconfiguring it for different setups was always a chore. Here's the easiest way I've found to do it:
1. Set "left" and "start height" both to 0.
2. Set right and total height both to 100.
3. Preview the screensaver and take notes as to where the little 100x100 pixel box shows up.
4. Use the Display Settings control panel to figure out what you need to adjust for all the settings.
I usually try to first lock down where the "left" needs to be. Depending on the location of my main monitor, it can vary quite a bit. But if you make it display a small box first, then lock down one corner of the box in the right place before adjusting the other variables, it's a lot easier.
The point is, the screensaver will display a rectangle. You just need to make sure all your monitors fit inside the rectangle. And if you want the title bar thing at the top, you'll have to make sure you have monitor space that fills the entire top of the rectangle.
That should make sense to some people. For the rest of you, I'm sure you'll figure something out on your own.
:)