In Canada you take the Level 1 and then teach first. Unless there's an extreme shortage somewhere, you'll only get a job teaching if you've got at least your level 1 (and most larger places, level 2). I know that some ski schools (private clubs in ontario, dont' know about elsewhere) have an assistant program, where you get paid basically minimum wage and help a certified instructor out with a class (usually young children), and the ski school will provide you with sessions geared towards helping you get your level 1.
DunDunDun, there are plenty of level 1 courses scheduled around Ontario. Goto www.snowpro.com/cisa/e/
and click on the level 1 link, they'll have a bit list there. You'll probably find something that works for you.