Does your class conflict with an orientation session or with round 1 parties?
If you would be missing an orientation session, try to find your rho chi in advance and explain the situation. She will probably be able to sit down with you one on one and tell you what you need to know (recruitment schedule, etc).
If you would be missing parties, that's more difficult. I think you said you have 6 national sororities at your school? If your round 1 parties allow for breaks (say you have 8 time slots, 6 parties + 2 breaks) maybe you can arrange for your breaks to be during your class time. If not, is there another session of your evening class that doesn't conflict with rush, that you can attend just for that one day?
Good luck!