Make a concerted effort to meet new people. Speaking to someone individually also has a greater impact than speaking to a group. However, time is often short, so make as many announcements as you can. You can usually make your announcements at meetings or in classes. Be sure to check with the professor in the latter case.
Faculty can be of great help with announcements.
The engineering and computer science faculty also can give good incentives to students who are still just thinking about attending the conference. Professors can be influential by offering extra points in class or by allowing students to miss a class in order to attend the conference. Phone numbers of EE and CS students can usually be generated by their respective departments or by the records office. Try not to limit yourself to EE students. Every engineering discipline can be approached, especially if you need a bigger audience.