I used a piece of plywood as a divider. I cut it so it was 2" wider than the crate, and cut notches with a jigsaw where the horizontal bars are. Then I slid the divider into the crate on an angle, and stuck it in one side between two vertical bars. I then had to pull out on the other side of the crate (bend it out) so I could swing the other side of the divider in place. Once in place, and let go of the side of the crate, the divider ends up having 'tabs' sticking out both sides of the crate.
If you can't picture what I did, let me know, and I'll take a picture tonight of the crate and put it in my gallery.