Button key assignment?

i made a game with wasd. i want it for android without changing code. is there a way to directly assign a button for a key? (e.g. Jump button = space bar or up = w) thanks in advance!

Xpressed = Input.GetKeyDown(KeyCode.X);

So you could do:

void OnMouseDown ()
{
 Xpressed = Input.GetKeyDown(KeyCode.X);
}

This would act as keycode true when whatever button you have is pressed.