Located in the same building as Chelsea Studios, home to the good people of Theaterworks USA and countless auditions for touring musical companies of former Broadway shows is hidden a small but cared for jewel called the T. Schreiber Studio. All one has to do is look at the plaques on the walls to realize that commitment to a craft is paramount here. One plaque is from former Vice President Al Gore, thanking Mr. Schreiber for his more than 30 years in the service of downtown New York theater. Another plaque from former mayor Rudolph Guiliani declares January 25, 1999,