If you already have a BS, I would recommend just self study and hands on training and maybe some night courses at your local Community College... If you do go back, make sure you know exactly what part of computer science you want to be involved in or you will hate it. Also make sure you get in with your adviser immediately and plot your courses out for the entire 4 years or they will make you take classes you don't want to fill in the spaces... And know who you are going to work with and start building that relationship while in college...
RE: Going back to college for a computer science degree! Second Bachelor's Pros and Cons