It doesn’t have to be terribly difficult, as I understand it, although I’m not an expert; the only reason I know anything about it is that I’ve investigated it for myself. The simplest way is probably to get a certain number of “points” on their qualifying test, which is available on the Web. It’s not terribly hard to get enough points if you have a reasonable amount of education and get a job offer there. The latter shouldn’t be too difficult if you have skills employers there are looking for. The whole process is supposed to be even easier if you are in one of the “NAFTA categories” for technical workers.