you could do this 2 ways.
Use a ‘spider’ (or spyder?) which is a device which will split an HD, SD or computer signal into 6 SD outputs.
This will let you ‘map’ different parts of the image to different screens. Not cheap though, especially for 6 outs.
Or you could burn 6 dvd’s and play them using a synchroniser. These are available from a guy in the states. Can’t remember where though. Much cheaper than first option.
I’d do an initial edit for timings in FCP, then export using auto duck and do all the graphics work in AE.
Make a 4320 x 480 size comp (6 x NTSC frames) and do all your graphics work in this. You’ll be able to see how your existing media stands up in this format.
Then render 6 movies out from this master comp, one for each screen.
Then burn to separate dvds.
AE is the way to go because the frame size can be anything you like. Also you can render out quarter size previews to save time. AE eats this sort of thing up. From experience, much better than flame, etc for this sort of thing.