You have the option of going as a normal student. If you do, top-tier colleges usually look at college and AP courses taken at other institutions as a bonus towards admission.
I went to Amherst College (#1 liberal arts college in the U.S. when I matriculated), having taken courses at Harvard Extension School, UMass Lowell, and Boston University as a high-schooler. They didn't give me credit for any of them, nor for the 8 AP tests I passed. However, I was told that they were a big plus on my otherwise-lackluster application. The fact that I could take and ace college courses at other institutions was a great way to nullify the fact that I was failing my high-school courses.
My sister did courses at Middlesex Community College (again, through the same MA dual-enrollment program that I used) and went to Rice University and my wife did courses at Foothill Community College (through CA's dual-enrollment program) and went to UC Berkeley, so not an isolated experience.