In order to define a contextual actual for map calculator layers, you need to put your Python script in your Python directory under a directory called Contextual_Map_Calculator_Layer.
Go to Tools->Options->Environment->Python Scripts (or Tools->Options->Python->Scripts in INTViewer 5.2) and click "Refresh from Disk". Your script should be listed automatically.
You will now be able to execute this script from the contextual menu of the map calculator layer:
This script will the time slice time value to be at half the distance of the maximum time range.
This script is attached at the bottom of this article.
The result after the script executes should look something like the following: