Talk to the faculty first. The institution has to participate to legitimize a work-study situation for some kind of course credit, and then everybody wins.
Most business schools love to put M.B.A. students together with real-world businesses for hands-on business work. If you just start with the main switchboard of the nearest business school and explain what you want, you'll most likely be connected with someone who can help you make arrangements.
I'm glad you ask, though, because you can make it win-win by arranging for class credits and avoid taking advantage of someone.
Question added to topic Grow Your Business • March 21, 2011
How Can I Get an M.B.A. to Help on a Project?
I would like to propose a business idea to an M.B.A. student as a project that he or she can use in class and gain hands-on experience.