Pick up a good algorithms text, study it fervently. After you're familiar with most/all of the concepts, apply for a computer science masters or computer science PhD program.

If you can demonstrate knowledge in algorithms and have industry experience in computational fields, I don't see why you could not be accepted into grad-level CS program. At this point in your career, I doubt a BS will give you more benefit than simply working more in the field (inclusive to furthering your understanding of technical problems and solutions).

If it's computer related you can teach yourself. You want to learn more languages etc. I think you would be better off learning programming concepts the right way from a CS textbook or some other computer science resource so that you are capable of learning every language. There really isn't that much to learn. Thousands of dollars worth of more school is not the answer in my opinion.