Tegan, I too am in for a sweep today, it will be my second one, the first was never going to work as I wasn't 'ready' last week, but since then I've lost my plug, so I'm guessing I'll be more favourable!
As for what it felt like, nowhere near as bad as a smear, wasn't uncomfortable or painful for me, but then I've had two kids already....lol, so that's maybe something to do with that!
Anyway, would just like to say good luck to all the ladies overdue on here, I don't post often on mumsnet, but I'm on everyday and would feel lost without it at the moment, its good to know there are others going through it just like you! Being 7 days over my due date, and my first false alarm being over 4 weeks ago now (damn third pregnancies)I'm right there with ya =)