not sure what you mean but if you are talking MEL script, then, for example if you downloaded the 'nuts and bolts' MEL from 'highend' you would copy that script into the /my documents/ maya/scripts

then you would open up maya (in that script there are 4 lines) you would copy or type the first line of the script into your command line (bottom of maya UI) and press enter and the window for that plugin will open and you go from there.

am not sure if this is what you mean, you probably know all this already.

umm?? (this is edit) just saw the image, obviously you do know the above, sorry.