SSBuddy improves on the existing soft selection editor for Maya by offering the alternative of the NURBS-based falloff editor, borrowed from the sculpting tools.
SSBuddy is designed to mimic the existing soft select panel, providing duplicates of the existing controls. This is to allow you to use it a complete substitute.
Run the MEL script however you like. You could add this to a shelf if you like, or source it from a file.
This is a MEL script that uses the falloff widget from the sculpting tools to manipulate the soft-select curves.
Run the script to create the control window. The curve automatically updates when it is dragged. To remove the large number of points the script creates and return to the default soft selection UI, use the Reset button.