Not much advice really, just thought I'd say that I recently did CC with my 8.5m DS. He settled with only 10 minutes of crying the first night, resettled himself during the night (on all his normal 6 wake ups, with no need for me to go in), that night. He then slept through he second night after only 2 minutes of crying.
I think sometimes if the baby is close to settling themselves, or if it is just bad sleep associations waking them up, they can take to CC without much pain on either side.
Otherwise try taking a look at The No Cry Sleep Solution, which has a number of ideas for sleep training without the need for crying.
How much is she sleeping in the day? Anything more than 2 hours or so may impact on her nighttime sleeping. Also, rocking her to sleep in the car seat?.. That can't continue surely? She will get too big eventually. You will all benefit enormously from helping her to learn to settle herself to sleep. How you decide to go about that, is up to you. I have used CC but probably never started from your point, as mine were fairly good at settling themselves.
DD has never been a great sleeper but has normally only ever woken 2-3 times a night for her dummy and has managed to nod back off straight after. However for the past 5 nights she has been waking up every 2 hours or so and she is wide awake! DH works shifts so can't rely on him to help too often so I've been surviving on 4-5 hours broken sleep.
The only way to get her back to sleep is to rock her in her car seat (same goes for bed time) but this can sometimes take 1-2 hours and last night she was awake from 9.45pm - 2.15am!
She is not ill, hungry or teething but I have tried calpol anyway. She has been in her own room since 8 months and there any no noisy neighbours or anything that could be waking her up.
I've tried CC before but I only lasted an hour and she made herself sick so I won't try again.