Hey, it's hardly impossible to do it with A. To Berserk_Ookami, there's two ways to do a shuffled Fair:
The first way is when you immediately use Fair as you jump, causing it to come out as you rise. Doing it this way is required if you want to perform a Short Hop Double Fair. If you only do one Fair this way, then the attack will end before you reach the ground, and you won't need to L-cancel. You can waveland or use another fair before you land, if you want. If you're having trouble fast falling with this one, make sure you wait until Marth is at the peak of his short hop height before you fast fall.
The second way is to jump, wait until Marth reaches the peak of his short hop height, and then fast fall, Fair, and L-cancel all at the same time. This is tough without the C-stick, but what you should try to do is work on 'rolling' the control stick downwards after doing the Fair.
GL.