I think what the phone representative was referring to was the fact that you can apply for credit once you start making eligible payments, so that you officially have those eligible payments on file. Whether or not that amounts to actually being in the program (in the event it gets cancelled, which I think it will, and whether anyone gets grandfathered in, which I don't think anyone will), won't be seen/known either until 2017 (when the first group of borrowers would be eligible for PSLF) or if the government clarifies or changes the program prior to that.
Still, it can't hurt to file your eligible payments--it keeps track of them, and in the event the program IS cancelled but people who filed their payments ARE grandfathered, well, then you're in the money.
There's a form somewhere out there. Either with the Dept of Education website or maybe with your federal loan servicer (FedLoan, NelNet, etc.) It has to be signed by someone in human services at the place you work.