How to create a button to run install script in magento?

I have created an install script.

But my requirement is, this script has to be run only when it is invoked manually. I have created a button in admin back-end. When I click that button the script has to be run. I have searched in Google. But I can't get any answer.

I don't know is it possible to do like this. How to prevent a script to be execute when that module loads first time.