Don't bring it up. They'll see it listed in the application, if anything.
Want to know what happened to me by bringing up my connections in my interview? I was waitlisted so I called the dean to ask how to improve my app. for next year. The interviewer wrote down "strong commitment to medicine, strong medical experiences, but may have used connections to get in with their colleagues to get the experience."
In other words, he implied I had it easier than most applicants to find medical activities since I knew tons of ppl in the medical field. I don't know what's wrong with that to be honest. If you have connections, you should use them because that's what gets you the best opportunities, at least for jobs. For admissions, I guess they see it differently.
I doubt that was the sole reason I got waitlisted, but it definitely didn't help having the rest of the adcom reading that comment from the interviewer. So, in other words, it probably won't make or break you, but it has the potential to do more harm than good.
Now, let's say you know someone on the adcom and they interview you. That can only help you. Basically, you can try using your connections but do not verbalize that you have connections.