To clarify, since generally the rope light itself won't be visible: Do you want just an object that looks like a rope light, or do you want one that actually generate light / illumination?
The object itself is probably most easily created just by tubing with a Morph if you don't need the lights.
If you want it to generate light, then doing so within ArchiCAD can be problematic given the number of light sources that will be present. If you have Dwight's book on Lightworks in ArchiCAD, follow his tips on neon.
In Artlantis, I think neon might be the way to go as well.
If illumination in a rendering is the goal, I should move this to the Presentation forum.
