Kangaroo Chain question (incomming newbie warning)

Hey guys, I'm fairly new to Grasshopper and Kangaroo and I am slowly figuring things out but there are a few things that I am stuck on. I am basically trying to recreate the catenary chain that is in the first 10 seconds of the kangaroo Video (link also at bottom).

My problems are:

how do I move the points in rhino and have them effect the points in grasshopper?

And

Generally how i make the chain, my assumption is that it is a poly-line with the endpoints set as anchor points, with a uforce or spring force on each of the points?

Thanks,

Kevin

Video: http://vimeo.com/8706003