1. Make a single block tall layer of stone blocks on the ground (5x5 for example)
2. Place a single moss block on top of the stone or place the moss block into the stone layer or place the moss block floating above the stone with an air block between it and the stone.  (any one of these methods)
3. Use bonemeal on the moss block.
4. All stone around or below the moss block does not convert to moss blocks. In fact, the only thing that is affected by the bone meal is the initial moss block itself which sometimes grows some grass, carpet or a tree on top of the moss block only.  

What I'm saying here is, if you bonemeal a moss block, it does not spread to adjacent stone blocks.