The way with the least amount of hassle is to just use the Texture deformer with “direction” set to “Normal”. Set the texture to all white, and then you can just paint the textureDeformer-weights. Then just play around with the sliders to get what you want.
At work, we just wrote a quick c++ deformer. And this is the perfect first c++ deformer to write because it’s so simple. All the data you need is available through convenience functions right on the MItGeometry object that gets passed to MPxDeformerNode::deform.