Newbie: How do I modify a laser pointer's button into knife switch(connected to...) ?

I'm having a trouble of how modify a laser pointer button. i want to turn it into a knife switch for my experiment. I will be doing a preliminary dissection on a simple 1mW laser pointer because I plan to do that green laser 100mW (which doesn't come cheap in my country). Can you guys show me how to do it? and also I want to connect it to a power source (modified from batteries). Thanks.

It's easier to do when the button is on the end, rather than the side. Just put the knife switch where the button switch used to be. (electrically, not physically)

the laser i'm first using is just 1mW *so that when i do it on 100mW i could successfully do it*. it's button is on the side. I dont know how to connect it. i'm doing this physically, but i want it working..

Well that's kinda like saying you're going to practice putting a door on a microwave oven so you get practice for when you put a door on your car.