Kristen,
I'm not really sure what kind of documentation is out there for this, from all the grumbling I've seen from other Eloqua folk out here I suspect it's slightly under-documented. Most of the good conversations can be found in this search: http://topliners.eloqua.com/search.jspa?q=salesforce.com+campaign+integration If you have specific questions I can help it's just a lot to write up all of it and so much is custom to your own instance in terms of how/where integration happens, etc. But if you've got some specific questions let me know and I'll do what I can to help.
Best,
Lauren