I just did this [I made 25 split screens]. Pretty easy, if time consuming - but I just placed the videos on top of each other and then used the transform tool to resize each of the videos to the proper size [cmd-drag is your friend to keep them relative]. If you want them side by side, shouldn't be too hard. You can even use the feathering tool to blend them.
Also, if you want sections, you'll have to crop them as opposed to shrinking them.