The number one thing you need before learning Jewelcrafting is...
World of Warcraft: The Burning Crusade
Once you have purchased the expansion (available January 16th, 2007) you may then find a trainer and learn the new profession. Until that time, the only people who would be able to tell you where the Jewelcrafting trainers are the beta testers and their information may or may not be accurate come release date.