How about rowing machines? Is that considered an eccentric action?
When I've climbed volcanoes with newbies, the cardio goal was to run 8 miles (hilly if you can find them) in an hour or less plus taking some good long day hikes with heavy packs on. Weighted squats and deadlifts would be good strenght training preparation.
How about mental fitness? While watching some of the documentary "Summit on the Summit", I recalled how much of a surprise it can be to newbies that a significant portion of the experience is suffering with wet gear, cold hands and toes, fatigue, physical pain, self doubt, fear of failure etc. Good partners (or guides) will help overcome some of these issues but in the end it may come down to confidence in your preparation and mental toughness.