This script allow you to offset the curves instead of adding keys, when changes are made in the viewport.
It'll offset the curves in there whole time, or if you first select keys in the graph, in the selected time range.
This script as to be used as a Maya shortcut in combination of "curveoffsetRelease".
To use it 
1 copy the two script "NP_curveOffsetPress.mel" and "NP_curveOffsetRelease.mel" into your /maya/scripts folder.
2 open maya
3 create a shortcut with the following line and the option set to "press".
source NP_curveOffsetPress.mel;
4 And create the same shortcut with the following line but this time with the option set to "release".
source NP_curveOffsetRelease.mel; 
