Hi Eric there is a MoI JavaScript documentation by David Morill that helps a lot when you're familiar with JavaScript.
http://moi.maxsm.net/api/

Here are some examples how to do some things in MoI using factories. Just look up the command you want to use and see what inputs are required. For instance for a line the factory requires two points.

Draw a line

script:
var factory = moi.command.createFactory( "line" );
factory.setInput( 0, moi.vectorMath.createPoint( 0, 0, 0 ) );
factory.setInput( 1, moi.vectorMath.createPoint( 40, 40, 40 ) );
factory.commit();

Draw a circle on xz (Front) plane

script:
var factory = moi.command.createFactory( 'circle' );
factory.setInput( 1, moi.vectorMath.createFrontFrame() );
factory.setInput( 3, 10 );
factory.commit();

Draw a box

script:
var factory = moi.command.createFactory( 'box' );
factory.setInput( 0, moi.vectorMath.createFrame() );
factory.setInput( 2, 20 );
factory.setInput( 3, 20 );
factory.setInput( 4, 20 );
factory.commit();

Draw some text

script:
var factory = moi.command.createFactory( 'text' );
factory.setInput( 0, moi.vectorMath.createTopFrame() );
factory.setInput( 1, "Hello World" ); 
factory.setInput( 2, "Arial" ); 
factory.setInput( 3, false ); 
factory.setInput( 4, false );
factory.setInput( 5, 'Curves' );
factory.setInput( 6, 10 ); 
factory.commit();

Just copy each script to the clipboard, hit TAB in MOI, paste the script and press ENTER.
Experiment and enjoy
Martin