how to play Mountain Goats - Big Mountain expansion

About Mountain Goats: Expansion Pack, from BoardGameGeek:

Mountain Goats: Expansion Pack adds a 5th player and the Big Mountain expansion to the king of the hill style game. The Big Mountain expansion offers an additional target for your goat, a big mountain. There is only room for one goat at each step in the path ascending this bigger mountain. However, only a few goats with the greatest ascent will earn points. Roll your dice and decide whether to compete for king of the hills from the base game or instead commit your goat to the big mountain. Timing is important on the big mountain. Goats committed to the big mountain may not even score depending on their relative position on the big mountain. The Big Mountain expansion increases the tension and impact the final few rounds. Additionally, this expansion increases the maximum player count to 5 which can be applied to the base game or the Big Mountain expansion. This was packaged together along with two other expansion in 10-Minute Games: Expansions, but is now available by itself as well.