Switch between third and first person controllers.

Ok, first off I'd like to apologize if there is another thread for this but a search turned up nothing. I'd like to make it so that when a key is pressed the player will stop using a third person controller (and custom vehicle) and start using a default first person controller (with a different collision detection and abilities). On pressing the same button again the player will switch back to driving a vehicle. I already have the controllers and cameras for each but how do I switch between the two on a button press. Additionally I'd like the screen to have a fade in fade out effect during the transition so it doesn't feel too weird. How would I go about doing this.