Silvercup studios is New York City's largest film and television production facility. It features 13 studio, a few drive in studios and is located in Long Island City. Only film is shot there and does not cast people through Silvercup. In order to be cast you must go through talent agencies, which could take up to months to achieve and years to even get a job through a casting call.
Though there are some other routes you can take you can become a production assistant in the New York area through NYC.gov - Mayor's Office of Film, Theatre & Broadcasting. There you can see films shooting in New York, guidelines if you want to shoot a film, and where you can apply to be a production assistant. Under Employment you will see P.A. training. “Made in NY” Production Assistant Training Program located in Brooklyn NY.
Alec Baldwin shoots his TV show at Silvercup Studios and "Sex and the City" with Sara Jessica Parker was also filmed there. But films are shot all throughout Long Island and New York and as we know we have plenty of celebrities living on the Island.
This is a websites you can go to, to connect with Silvercup Studios, good luck and keep me posted if you decide to try this program out. http://www.silvercupstudios.com/