Phil,
Sounds like u didn’t do u homework, or u are willing to risk getting screwed over by the employer and possibly get in legal trouble with the govt.
If your employer is legally able to hire a foreigner, then they would issue you a Z visa first and you would come over on that and then the school would get your work permit.
Sometimes schools will use an agent or a company that will “sponsor” you, but that would mean that your particular school does not have the legal ability to actually hire you. Or, as with many, they will tell you something that is not true, or you may agree to their arrangement, but technically you may still be working illegally, and thus could suffer the consequences of such action.
What is the school? It’s possible someone here works there or knows the place and can give you some info.