I put my IB exams (along with my AP exams) in session 1 of my freshman year as "Advanced Placement." I'm not sure if its exactly how you are supposed to do it, but I think it works out. It's not factored into GPA anyway, it just shows the schools that you took them.
I think you're supposed to only list tests that show up on your college transcript, maybe that's wrong but that's what I did. I don't think another few IB exams would make much of a difference anyway.