Have you contacted Pontiac Historical Services yet? It doesn't take a phone number to do that...
www.phs-online.com
That's all you need to order a package from them, although I still can't speak for if it will accomplish what you want. If you really, really need a telephone number, they list a fax number. I'd imagine you could send a fax requesting a telephone number to call for information.
Another option, which you may have tried already, would be to call the 1-800 number listed on that website for the Pontiac Customer Assistance Center (1-800-762-2737). I would imagine that somebody there could get you in touch with PHS.