I stumbled upon this forum and found USC TAP in the conversation threads! Just wanted to add that I applied to TAP after my freshmen year and got in. Just from hearing about it from friends, I think it's relatively easy to get into. Everyone I know that applied got in. I think the program is mainly based on grades (contrary to a previous post that it's based on extra currics). Also now they don't require a writing sample or an interview. These requirements might change in the future, however.
In regards to how its publicized, I definitely agree w/ the other posts. They don't publicize it as much as its Bac/MD program, and I only knew about it by word of mouth and by one of their small info tables @ open house. This info table was hidden away in the corner and I probably would not have discovered it if I didn't browse the fair thoroughly. Its lack of publicity, however, is beneficial because the competition to get into the program is definitely not as high as it could be!
Hope this helps anyone out there who might be thinking about applying! I highly encourage it! It beats having to worry about apps after senior year & thinking about how much extra currics to do when you're just trying to concentrate on GPA.