How to I slice holes in walls?

How to a efficiently cut holes in walls without unions? I have looked around the web but nothing seems to work for my needs. I found a good script that can cut a hole but it has problems

All I'm trying to achieve is the wall hole moving with the part, kind of like a boolean. The wall is never know as this is in a function that is called when the mouse moves and it finds a target wall.

The code used in the example is hard to understand and wasn't created by me. Original can be found here