You don't go underneath the car, you can do it all from the driver or passenger seat. I don't recall yanking on my e-brake cable when I installed my SVT handle, but it's been awhile. When you unbolt the old e-brake it becomes apparent how to take it off and reattach the new one, hard for me to explain since my memory's fuzzy.
Definitely covering the new handle with a sock or whatever is a good idea. Removing my console didn't scuff the console but it Did gouge the crap outta the underside of my old (thank god!) e-brake handle. I was very cautious getting the console back on over the SVT one!