Controll with joystick

[Wardog254]

I'm using a Saitek Cyborg Graphite joystick to play gta and I wanted to be able to accelerate by tilting the joystick forward but can't figure out how to do so. I am able to steer left and right and tilt the camera angle up or down using the joystick and can use the joystick's buttons to accelerate but I want to be able to have a slower acceleration like I would with the pressure sensitive ps2 controller. I also don't wanna go out and buy another game controller since I'd never use it in any other game.