It seems as though the reason why there isn't anything obvious is because there isn't anything in the contract...
I searched through various news outlets (New York Times, Village Voice, gotham.com, Workers News, Nexis) and couldn't find anything about a cost of living increase, other than the clause in the previous contract negotiation of 2002. I next checked the union's local website: http://www.twulocal100.org and still nothing. So I called the union and spoke with one of the representatives and he said that there is nothing about a "cost-of-living" increase in the MTA contract currently being negotiated.
For more information you can contact the union at TWU Local 100 Headquarters
80 West End Avenue, New York, N.Y. 10023, 212-873-6000