Yes exactly. You guessed it right
As an IMG, you have essentially a 0% chance of matching to any of the 3 Harvard surgery programs (MGH, BWH, BIDMC). Just doing a rotation at any of those places will not be nearly enough to get you in the door. Those are some of the most competitive programs in what has become a reasonably competitive specialty. Do not waste your $3,700 or whatever insane fee they charge for doing a rotation there.
If you are dead-set on doing surgery in the US, you need to set your sights on community or university-affiliated community programs that have a known track record of taking IMGs. Last year (2014), there were only 76 IMGs who matched into categorical surgery out of over 1,200 available positions.
If you are ok with being miserable, having to go through the match twice, and committing to spending a year in the US with the very real possibility that you will come out of it without a full residency, you could also match prelim surgery (these are relatively easy to get) and try to do so at a program that has a record of taking their own prelims. If you go this route, know that there is a very real chance that you will not be able to continue your surgical training beyond your first year as a categorical spot is far from guaranteed after a prelim year.
Your chances of getting lower-tier IM, FM, Psych are much higher if you are dead set on coming to the US to train regardless of specialty.
Also, since you are still in school remember that if you want to be considered for a residency you need to take the USMLE and get ECFMG certified, which may delay your chances of coming here for next cycle.