If you have a bunch of CBZ files in a format:
SomeSeries/chapter1.cbz
SomeSeries/chapter2.cbz
...etc
This tool (with a help of small text file) with combine all CBZs into one EPUB file.
perl makeEpubFromCBZs.pl book_description.txt
where book_description.txt is file with format:
name=Name of the Manga
author=Name of Author
intro=Some description for that manga
chapters=C:\ComicBooks\Folder\
cover=chapter1.cbz/003.jpg
If 'cover' is ommited - the first image from the first chapter would be used.