Source code for the sePushPullConstraint plugin for Autodesk's Maya. The souce code is licensed under the GPL v3.
For compiled versions of this plugin and for more details, go to the sePushPullConstraint page here: http://www.scottenglert.com/projects/maya-plugins/sepushpullconstraint/
You can use CMake to compile the plugin yourself. Also there is the Python version of this plugin if there is no compiled version for your system.