MEL scripts are very useful pieces of code that can add new tools, options, and functionality to Maya. These scripts can be saved out as a separate file and installed or activated on different systems.
To install a script that you acquired, first, move the .mel script file into a location where it won’t get moved around too much. When a script file is moved, it needs to be re-connected in Maya. By keeping it in one place, you won’t need to find it again.
Once the file is ready, open Maya and go to “Window > General Editors > Script Editor”
In the Script Editor window, go to “File > Source Script".
Browse for the script you want to load and open it.
In the MEL section at the bottom of the main Maya window, type in the script’s name without the extension and enter. For example, if the script file is called “Customscript101.ma”, type in “Customscript101”. If you get an error, try shortening the name a bit more, such as “Customscript”.
The script or tool should now be running and ready to use. If you restart Maya, the script will already be loaded up and all you’ll need to do is type in the name of the script. If you’d like a faster way to access the script in the future, simply type out the name of the script in the MEL area, select the text, and middle mouse drag it to the Maya shelf. This will create a button you can press to run the script.
Important: Keep in mind that you are not able to place custom scripts on the AM Shelf. When you close Maya and re-open it, the shelf will rebuild itself and clear out any custom scripts added to it.