I just made a couple small tweaks the Mel script i wrote to fix an issue getting blend node, and shape orig node. I think eventually i want to write something using c++... (also there is currently a bug i'm still working out if the base mesh is part of skincluster.. i think some additional fixing is needed if the base mesh has incoming blendshapes and has a skincluster). Also Using c i think i could be able to modify blendshapes quickly if there are no topological changes to base mesh. Also I think later with the c implementation i could be able to automatically mirror a fix to one side of a blendshape to the other side... i probably could reuse some of the code i wrote to make corrective shape using maya api.
Please check it out (its still a work in progress)