NEEDHAM - You may think you have what it takes to get into a selective college - high SAT scores, a beautifully written essay, and 4.0 GPA. But can you work with total strangers to build a 2-foot tower with little besides paper and foam board, while caped college students wheel by on skateboards and bikes, then serenade you? Dozens of high school seniors gathered yesterday at the Olin College of Engineering for an innovative admissions process designed to determine the ability to fit in at a campus that prizes social skills and collaboration.