Building custom tools

Hi

Can someone give me a high-level overview on what the process is for building a new tool in adobe Illustrator? If it's even possible.

As an example:

I want a new tool that looks similar to the direct selection tool icon sitting over in the tool pallet. I'm calling this tool the "Zero distance tool". When I select this tool and click an anchor point from two different object it'll move the objects such that those anchor points are exactly on one another. I don't need programming help unless it's relevant. I'm experienced programming in C++ and JavaScript. I do not understand the workflow for building a tool like this.

Thank you.