I'm assuming you need CS majors. I'm in the same boat and this is what I'll be doing. I'd therefore recommend doing the same.
Print fliers and put them on the CS department's bulletin board at the nearest college/university
Check the nearby university's course schedule. If there is a related course, show up and talk to the professor (5mins) and leave the above fliers with him for his students. Focus on how this would help the student ("they will get to apply X in real life") vs being self centered ("I need interns").