It definitely is possible. You could also major in Art and minor in French. If you apply to major in French you should be able to get in for next year.. you will need to get a B- in the class you are taking now. You should check the Course Calendar though to make sure you will meet all the requirements.
As for art, you might be able to apply for next year. Usually the portfolio interviews are held in February or March, so it's probably not too late to apply. You could talk to somebody at the SOTA office, the website is here: http://sota.mcmaster.ca/
and the office is on the 4th floor of Togo Salmon Hall. The portfolio interview is very informal, all you do is bring in about 20 pieces(or photos) and a sketchbook and talk about your work. Then you'd find out around April I think. It's competitive to get in as it's a really small program but they tend to take special consideration for students already at Mac.
Definitely take Art History 1AA3 because it's a required course for the art program and so is Art History 1A03, although they usually only have that class first semester. If you haven't already taken it you could take it next year though. Also, there are usually some French courses offered over the summer so it might help you to consider taking summer school to get ahead a little. As someone already mentioned above, you should really talk to an academic advisor... they will be able to tell you what to do.