HELP!!!

My prom is this saturday, may 18th, and I have no idea what to do with my hair. I want to wear it in a demi-frence twist, but I want it curly.
I have medium straight light brown hair, and I really want it curly. I thought about Oglivie 7-day curl, and then going to the salon on saturday morning (I am also going to a wedding that afternoon), and getting it pulled back, but mom and dad said one or the other, not both....either I get the 7-day curl and find a way to do my hair myself, or I don`t get the 7-day curl and I go to the stylist. Curly hair is very pretty, and I REALLY want it, but hot curlers, and curling irons don`t last more than a few hours, and I want my hair curly for a few days....Any ideas? Also, I need a french comb. Where can I find one? I looked at Kroger (grocery store), but they did not have one.
My dress is long light yellow, with light silver sparkles, and has spaghetti straps.

Have you talked with your stylist? I think you should ask him/her what your best option is...although perhaps you shouldn`t mention the "either or" clause so he/she isn`t influenced by the possibility of you NOT coming to the salon, if you know what I mean. Have you ever done the 7-day curl on yourself? Because I would hesitate to do anything that changes your hair texture, even temporarily, since that can turn out disastrous if something goes wrong. Have you ever tried steam rollers? They sell a Caruso set at Sally`s and they`re not damaging. You might find the comb at a beauty supply store as well.

Something else you might try to get a curly updo....it`s cheating but is easy and cheap. Target sells these scunci ponytail ties that have faux curly hair wrapped around them. (about $3.) You can get them in black, brown, red and blonde--if you`re lucky enough to have hair that matches one, it is such an easy way to get an elegant updo. I pull my hair back into a bun, bobby pin it in place them wrap the scrunchie around. I get more compliments on that easy little style than when I spend precious time drying it straight in the morning to wear down! No one believes me when I tell them it`s not my real hair. I don`t know if this will help you, but good luck!

Thank you Lyris for all your advice. I know what you mean about the stylist...they will do anything to make sure I come there. No, I have not tried the 7-day curl before. Perhaps that is why my parents are so hesitant on letting me get it. My mom said they have stuff at the salon that will make my hair curly for a day. I am planning on just going to the salon on saturday...plus, my parents said they would pay for that, but if I got the 7-day curl I would have to pay for all of that.
Thanks again for the advice. I DO plan on having fun...