Can I come back under a new J-1 after completing my training

Hello, I am a Canadian landed immigrant since 08.2008 (originally from Burkina Faso), while I was doing my academic training in the US under a government funded J-1 Visa. I came to the US under a J-1 for a Master degree in July 2006, and completed an academic training after graduation, until Dec 2008.
After completion of my J-1 program, I returned to my home country in last January, and came back to the US two weeks ago under a B-2 visa, before I head up to Canada to start school in Jan. 2010. In the mean time, I have a 6 months internship offer before the start of school (July 09 to Dec 09) from my former academic training employer, and was wondering whether I am eligible to come to the US under a new J-1, or which kind of visa if any, will be suitable to fulfill this internship?
Thanks for your comments and answers.

Well one thing you need to careful of as a Canadian LPR is that you don't end up losing it by spending so much time outside of Canada - three years out of the last five is the limit.

You could do the internship on J-1 provided they are State Dept. registered and can issue you a DS-2019 for it. Or they can issue you an I-20 and you could do M-1.

You can only stay in the US for up to 183 days as B-2 (unless you renew it, which is hard to do in your situation). You can apply for change of status using form I-539 although I've read several times USCIS doesn't like to do B-2 to F-1/J-1/M-1 because they think you should have entered as that to begin with if that was your intent and gotten the appropriate visa. For Canadians in this situation it's not a big deal because they don't need visas but you would.

I suppose if they refuse to grant change of status you can leave and apply for a visa from Canada, which is possible because you are a Canadian LPR.

Thanks for the quick reply, I really appreciate it!
I am heading up to Canada at the end of April, so I think I will be okay for the residency requirement. And I intend to apply for the visa from Canada, before coming back for the internship, not file for a change of status from B-2 to J of M.
However, can you give me more detail on how the I-20 and the M visa works? I am not familiar with that.
Additionally, I would like to know if it is possible to work in the USA under an F-2 visa? And whether I should consider that option, since my fiance (from Burkina also) is studying in the USA under an F-1
Again, thanks a lot.

You cannot get work authorization in F-2. M-1 is similar to F-1, but it's designed for vocational education, e.g. if you want be a chef you have to be able to work in a restaurant.

Another possible option is H-3. Depends on the nature of the internship.