NEW YORK (AdAge.com) -- How is Eddie Murphy playing an invisible role in the new push to diversify ad agencies? Former agency account exec Lincoln Stephens is both an example and an evangelist of this Hollywood phenomenon. A year ago Stephens abruptly quit his Chicago agency job, moved back to his hometown of Dallas and, on a shoestring budget, personally launched a program to recruit, train and motivate college-age African Americans for advertising agency jobs.