How to launch a mesos task on a particular executor?

I am writing a mesos framework and I want to execute my tasks using my custom executor. I went through a couple of other mesos framework codebases (chronos and marathon) and wrote a scheduler that execute shell commands using the default command executor. Now I want to replace the default executor with something custom. The problem is I can not figure out how to register an executor with the slave. The documentation on building a framework states that it should be an executable and you can provide the path using executorInfo but I don't see exactly how to do it. Also, what's the point of having the Executor interface that every executor has to implement and at the same time requiring an executable on top of all that? What are the arguments to the executable?