I think it's probably one and the same. If she was sleeping through the night, she wouldn't want to nurse then, and if she wasn't nursing, she'd probably be sleeping through the night.
I tried to cut out the middle of the night feedings first - it was hard and I never had the heart to do the crying it out thing. Mostly I just had my husband do the rocking then; even when they would cry I didn't feel as bad because it wasn't like I was leaving them to cry by themselves.
After they stopped waking up for those I still had the one before bedtime nursing, and I actually held on to that for a really long time - and when I did eventually stop that one it was also by having my husband take over the bedtime.
Just do it slowly and don't do anything that isn't comfortable for you!