You have to use a scripted trigger, set up like this:
The delay between the Briefing and PropAnim is important. It doesnt have to be at 3.
To animate the rope is the same as with other pawns.
There are 2 heights that you can rappel from. 1760 and 600. It is a good idea to make the platform you rappel from as close as you can get to one of these, off the ground.