I just cut it with a kitchen knife, it was alittle annoying but it only took like 10 mins. And the diverider fit perfect! im so happy because i did not feel like cutting another one.
depends on your measurements. if you can get it to the point where your using solid squares then i have a 10 second trick. measure out the size you need and start cutting down about 3 squares. then take a wrench and let it slip into the path you just cut out. get some controlled momentum and slam it down. it will be a little messy but thats what cleaning is for.