there's a lot of molasses info here
as far as i know it's the black treacle not the golden syrup. i haven't used it yet but i read somewhere you just add a teaspoon to 5 liters of water and the plants love it, it's meant to be great for the flowering stage of plants. you may also want to boil a cup of water and add the teaspoon to that first, then add that to the cold water.
i don't think you'll get away with using just molasses