I've had lots of frustration trying to get my library's Overdrive epubs onto my Nook Color. I have not rooted my NC. It's original issue.
I have recently used the instructions in this YouTube video, however, and it worked liked a charm:
Substitute the name of your library system for the one that produced the video. I've talked with a tech for my local library system and, at this point, there is no work around for my B&N Nook Color to first downloading to my computer then transferring the epub as described in the video to my NC.