http://www.canadavisa.com/canada-immigration-discussion-board/-t45804.0.html
PNP varies province by province, so you would have to research each one. Most require a job (i think) but until you read it for sure, you won't know. I just dont know about PNP because i haven't looked at it.
If you are in the US on a H1b then alberta's H1 program is good.
The other is to find a job in Canada first but it is tough to find a jbo in Canada as a professor from outside. I know someone who is really really very excellent at what he does and I think universities are interested in him and he is in Canada but they won't hire him because he is not a PR yet. He has published a lot of papers while doing his postdoc in Canada so you can imagine how tough it is to get a university job there while not a PR or citizen at least at early level.
This is true for university positions but I don't know about colleges.