Drilling holes in the PVC is very easy. No need to worry about it cracking like when drilling glass or some other types of plastic sheets. The only thing you have to watch out for is too much heat as you can melt it to some extent. You just have to find the right balance between how fast the bit is spinning and how fast you can push through the material. (this is pretty easy, your nose will tell you if you are getting the PVC too hot)
The divider itself might cover part of the hole. This is what the holes AP machines into the top of the cage for the fluorescent light fixtures looks like:
The hole itself is 1.125" in diameter and is located 4" in from the back of the cage. They then route in a slot for the cord. This slot is so you can stack cages one on top of the other without any gaps, and to improve the aesthetics of the cage, but aren't necessary as long as there isn't a cage stacked on top.
Worst case you can use something heavy to cover the hole tom the outside of the cage.