You can't. If that pin is not an interrupt pin, you can't make it generate an interrupt.
You can fake it however - use a timer to scan the button n times per second, and if it's on (or off, or just transitioned, you decide) you can write some code. And since the timer only triggers in an interrupt, the code will be executed in an interrupt. You can use this method to add "interrupts" to more pins, but it will add more processing overhead.