I want to drive a cable up a cupboard. The shelves are too long to simply put the cable behind them, so I want to create an indentation in the removable shelves.  

[![enter image description here](https://i.stack.imgur.com/YXmT0.png)](https://i.stack.imgur.com/YXmT0.png)

I do not own a drill press, and I do not want to buy one just for this. I do not even have the space for it. How can I do this with only a manual drill? Is [milling](https://en.wikipedia.org/wiki/Milling_%28machining%29) a good idea, or should I press the shelf between two parts of wood, and just drill it? 

As this is on the non-visible side of the shelf, a V shaped cut with a saw is also an option.