Cusco [1] is a center for a range of spiritual and esoteric activities, though the main operators seem to change constantly. A good touchstone and longtime expert is José (Pepe) Altamirano, the owner of the agency Gatur (Puluchapata 140, tel. 084/22-3496 or 084/22-7829, www.gaturcusco.com [2], prices vary, call ahead).
Tourists are shown traditional practices by native healers with Back2Nature (www.back2nature.no [3], prices vary, call ahead), owned by Norwegian Irene Kingswick and Peruvian Dennis Alejo.
Many Cusco agencies, including Enigma, offer sessions with the ayahuasca hallucinogen. Leslie Myburgh at Another Planet (Triunfo 120, tel. 084/22-9379, www.anotherplanetperu.net [4], prices vary, call ahead) and Diane Dunn at Paz y Luz (tel. 084/20-3204, www.pazyluzperu.com [5], prices vary, call ahead) in Pisac [6] are other good contacts for ayahuasca and San Pedro ceremonies.
Links:
[1] http://www.moon.com/destinations/peru/cusco
[2] http://www.gaturcusco.com
[3] http://www.back2nature.no
[4] http://www.anotherplanetperu.net
[5] http://www.pazyluzperu.com
[6] http://www.moon.com/destinations/peru/the-sacred-valley/pisac