Follow the comments (the lines beginning with -- or sections enclosed with I think it's [ and ending with ]) for how to work the script, and in your ini code, add "ScriptPath = ..." on the same tab line as PresetName pointing to where in your .rte you place the .lua file.
That is, if you're working with a premade script. Visit the lua making forum if you have trouble.

ColorBomb, it may also help to specify whether you want a craft with controllable weapons or automated turrets.
Which brings me to my quick question, as to whether one could just pin an ACrab or an Actor to something, as the actor would target something normally, but I was unaware if there were any nasty tricks to it that would cause an actor as an attachable to not work.