Script to override motion while animation plays

Ok, below is my attempt at explanation of my situation, the top version is just the facts.

While Player holds Fire1 for animation his forward motion (arrow key) comes to a stop. If Player Character comes to stop below (10mph) then Fire1 is over ridden.

Imagine if you will...

A guy flying down the road away from the bad guys, he has a machine gun on the top of his car however he has not found his buddy to man the gun. He can hit Fire1 to switch to the gun animation firing endlessly until the car almost comes to a stop, then it switches back to drive.

Thanks in advance!

Set up booleans to check if the speed is too low. If it is, stop the animation.

At least I think that's what you want. Your question is a little light on facts.