You're not going to get a specific paint code. I tried looking it up at my shop there is nothing listed. Best thing to do is go to a Bodyshop and have the painter grab the gray color decks. Then find one that matches and have them mix up some touch up.
I can't help you on the color code, but I just want to extend my condolences. Hope you're able to get yours fixed up well.
I had Volk TE37SL Black Editions on my last car for 7 years and never curbed them once. Four months into owning my S650 another vehicle cut me off as I was making a right turn into a parking deck and I put the driver side front wheel into the concrete sidewalk/curb and curbed the shit out of the wheel. Eventually I'm going to put new wheels on so l haven't fixed it yet.