I wonder if I call my dealer, if they'll install them for that. :-/
Doubtful, but doesn't hurt to try and ask though!
If your dealer is anything like mine, not a snowballs chance. As far as not hurting by simply asking - be careful. I truly hope your experience as a new car buyer has been much different than my own, but I've rarely had a dealer that I felt comfortable touching my vehicle after the initial sale (GM, Hyundai, Dodge, Mazda, etc.). Mitsubishi, was the only dealer that took care of my ride when I put it into their care - a 3000 GT SL - many years ago. After that, its been all down hill. I take it in for one thing and get it back with several things - all bad things, of course.
Be aware that the roof panel of the CX-9 is rather flimsy. It does not like being pressed on with any amount of force. To install those roof railings, a technician will have no choice but to lean into your roof to some degree. Thus, you have to ask yourself:
Is it worth the risk. For me personally, the answer would be an unbridled, no. I like the look of the CX-9 with or without roof railings, personally. I would not risk having a devil may care technician leaning into it and causing more damage than its worth - only to have that same dealer call in their "paintless dent repair guy" to fix what they just screwed up. Sorry, that's too risk for me, personally.
I'd rather spend the time, energy and effort learning how to install them myself - if I really wanted it that much. Else, I'd ride comfortably without them. To prove this to yourself, just go up there the next time you wash and detail it. Use a small step ladder or shop step and start washing the top side of the roof. You will quickly see what other people talk about when they say, flimsy.
So, no. It does not hurt to ask, but it could hurt to have your dealer touch it! Just, FYI. Be careful.