There's supposed to be a version of Zulu Reader that's for some versions of CE according to this thread...
https://www.mobileread.com/forums/showthread.php?t=32551
The website is
www.zuluexpress.com but appears down right now. The developer is also a member here, username ondabeach.
Zulu is for non-DRM'd ePubs. If you're looking for a way to read DRM'd ePubs you can't AFAIK. You'd have to remove the DRM.