Honestly, the absolutely easiest way to make fondant ropes is to use a clay gun. Clay King sells some big ones, but I am not at all happy with the model that I have (the medium size one).
For all of my fondant ropes, I use the Makin's Ultimate Clay Extruder. That thing very easily extrudes out beautifully even ropes of fondant darn near effortlessly. Here's the link to where you can buy one online: http://www.craftsetc.com/store/item.aspx?ItemId=61576
If you want to do them by hand, I recommend using a large piece of fondant with either some gumpaste or Tylose added in, and then rolling a big fat snake. Take a cardboard cake circle and use that for rolling the snake thinner and thinner until you have a rope. The cake circle will help you keep it even and makes rolling it out easier than using your hands.