Hey matty and soccerchic.
I'm also waiting for the AIM letter and did some research on this lottery system.
I found this AIM flyer that explains the program to high school juniors.
On the second page, it says:
"
In the event we cannot accommodate all applicants, a lottery will be utilized to choose among eligible applicants.
So I think that they accept people who have the qualifications regardless of the quota. In the end if there happens to be a larger number of qualified applicants than the quota can hold, then they will use the lottery system.
Here's the flyer if you guys are interested
http://schools.wcs.edu/bhs/announce/Miscellaneous Flyers/Aimflyer.pdf