By train
The Ferrocarril Central Andino (http://www.rrdc.com/op_pe...) the train line joining Lima to Huancayo, is the second highest railway in the world and the highest in South America. The journey on board the Train of the Andes through the heart of Peru is simply breathtaking. It is an 11-hour experience where the train reaches an altitude of 4781 m. 15,681 ft., goes through 69 tunnels and 58 bridges and makes 6 zigzags. In 1999, the company was privatized, in 2005, Ferrocarril Central Andino renovated their passenger wagons. Unfortunately for time-limited travellers, it only runs twice a month.
Other
During the day, there are always colectivos to and from Jauja. Colectivos to and from Lima are also available for under $15. In Lima, have a taxi driver take you to the Yerbadero. In Huancayo, ask your taxi driver to take you to colectivos to Lima. These will be found a bit out of the city center on Real Street. Lonely Planet also talks about a company called Comite 12 that has a station right around the Municipalidad.