Mate, the only thing you have to do on the motor side is unbolt the nut on the steering cable and the whole unit will slide out of the motors body, may be with a tap or two, even if the cable is stuck.
The time is in the helm, If you are not replacing the helm, to take the steering out if there is no room, take the lock pin out, slide the old cable out, feed the new cable in and put the lock pin in. And tuck the cable back away where it was.
Thats it. you can do it your self.