I don't really remember the fine details of our chapter's pref ceremony, because I only saw it once as a PNM and then once as a sister, because my last two years I was a Pi Chi and on Pan Exec, but I'll tell you what I remember.
The PNMs are serenaded as they walk in the door by sisters singing "The White Rose." We serve food at ours, and the first half is spent with one PNM paired up with a sister, and the two of them talk just like they would at a normal party. Usually people are paired up with their "rush crush." The PNMs are given a white rose and then go into a different room.
For the ceremony part, the PNMs sit in a semi circle, with sisters standing behind them. VP Recruitment usually starts a little speech which leads into the chapter singing "It only takes a spark" and we start lighting the candles at each end of the circle until they are all lit. Then a couple sisters will give testimonials about what KD means to them, or how sisters helped them through a hard time. Usually we all end up crying at the end of those! Then the President will start a speech about how many different people make up our chapter, and all the seniors go to the middle of the circle and stand in a semi circle facing everyone. The President says something like "Without me, there would be no leadership." She takes a petal from the rose and drops it on the floor. She passes the rose to the next senior, and she says something like "Without me there would be no laughter," then she takes another petal off the rose. It keeps getting passed around, some of the other things are friendship, love, honor, faith, beauty, truth, pride, spirit...you could really use any positive adjective that reminds you of KD. The last person to get the rose is the New Member Educator and she usually says "Without me, there would be no sisterhood, and without that, there would be nothing at all. Just as this rose, the symbol of Kappa Delta, has been stripped of it's petals, without sisters, our sorority would fall apart." There's more to the speech about coming home to KD, our motto, stuff like that.
Then she invites the PNMs to come up to the table and make a wish. Each sister leads their PNM up to the front table, where the loving cup sits, and she tells the PNM to pluck a petal off the white rose and make a wish as she places it in the cup. Usually after they do this, sisters will whisper something like "I hope your wish is the same as mine," or "I hope your wish comes true," or something equally cheesy. (Sorry, I know it's bad to say it's cheesy, but almost every sister says the same thing, and then PNMs will talk and say "what did your girl say to you" and they'll find out we all say the same thing! And also, I know at my school Tri Delt does a similar thing with dropping a pearl into a fountain, and a lot of them also say "I hope your wish was the same as mine"

)Then the PNMs are walked out the door as the chapter sings "Dream Tonight." That song got so stuck in my head after I went through, there was no way I could put anyone else by KD down for #1!
If you have any questions on any of this, let me know. I'm sure I was rambling! I loved prefs, that was the one day that I really missed my sisters when I was a Pi Chi. When I got back on bid day and slept over at the house, I made my best friend sing "Dream Tonight" for me before we went to sleep!