With these blend tools, I implemented my own PSD-system (pose space deformations). This allows for easy fixing of problem deformations. Blendshapes are modeled in posed space and converted back to bind space before they are applied.
It is a simple 2 button proces where the first click prepares the model to be sculpted and the second applies the shape in the front of the deformation-stack.

The model to be sculpted is completely separate from the rig so you can use whater tools you want to sculpt in the correct form. In the demonstration video below, I use export/import OBJ to send the model to sculptris to fix it. Setting detail to zero, sculptris will not add any vertices and the index order after importing it back in maya will be the same as it was when I exported it. Ofcourse, GoZ is also an option.
The 'base' and 'def' fields (not shown in demonstration) is a means of attaching a regular blendshape to the rig. 'Base' points to the mesh being driven by the rig and 'def' is the deformed blendshape. If both fields are filled, the conversion of pose-space to bind-space will be skipped and the def-shape will directly be hooked up to the rig.
This is usefull when adding symmetrical blendshapes. It is quicker to attach the reflected bind-space shape directly, rather than go through the pose-space to bind-space conversion.