The new 2.2 release now comes with a headless / no-GUI / command-line console (whichever term you prefer).
You can run your scripts (and Python scripts) by specifying them in the command line, like
I've tested the console to a certain degree, but there may be some bugs here and there. Also note that certain Maperitive commands that are GUI-specific don't do anything in the console mode.
There are also two parameters (-viewwidth and -viewheight) which you can use to set the size of the Maperitive console virtual map display. The default size is 1000x1000 pixels.
I doubt you will really need to use these two parameters, however - they are only useful if you rely on a certain display size in your scripts when exporting or generating rasters (which you shouldn't). Specifying the bitmap size explicitly in the command parameters is a much better approach.