Hello welcome to AD, yet another minnesotan yahoo! 
Well, as your question..
For me, here in minn terp code of ethics.. is the same as the Utah code of ethic that Deaf258 provide above.
I would suggust you to simply ask the boy permission first, then ask the terp when is the best time.. As for class.. I think it's best not to.. but if he accepts it and the interpreter accept it then it will work. There's always other way to shadow other places..
as for me, I won't let anybody be a shadow while i'm in doctor's office because it's too personal or other personal conservation. Classes are fine for me, as long they don't chat to eachother 
