There are numerous guide/outfitter schools, all the ones I have seen are in the west. I am a booking agent, and one of the Outfitters that I represent also has a guide school. Check out
http://www.russellpond.com/guideschool.html Let Joe know I sent you, if you contact him. To actually become a guide probably depends on the state or province that you are considering. I had my Guide's License in New Brunswick, where I was born and raised - you had to pass an exam, and pay a fee. Hope this helps.