For third party toolboxes, there will either be an associated python script or the script will be embedded. Check the properties of the tool to see if there is a source script file. If embedded, right-click to export script. There may be password protections.
If it is not a tool, and it seems in this case a model tool, the model can be viewed and modified in model builderModelBuilder. Simply right-click and edit. From model builderModelBuilder, you can also export the script to modify or use in a python script tool.