Scripted Utilities appear in the Utilities Panel > MAXScript Utility. This used to be the main script type in the early 3ds Max versions (R2.x). Many older scripts are still available as scripted utilities. In addition, scripted utilities are probably the easiest to write script form since they are a special case of rollouts and can save the developer some UI management work.
Scripted utilities have the extension .ms and contain the constructor "utility" in the source code, something in the form of:
utility someName "Some Name" ( ... )
To run a scripted utility (single3ds Max session):
Go to the Utilities panel, open MAXScript Utility, press Run Script... (Alternatively, go to main menu, MAXScript, Run Script...)
Locate and select the .ms script source file and press Open. The name of the utility will appear in the "Utilities" drop-down list.
Select the name of the Utility from the list - the scripted utility will open in the Utilities panel.
To install a scripted utility (multiple3ds Max sessions)
Topics:
MAXScript for New and Casual Users
Scripted Plug-ins for New Users