Chmox is one of the simplest software to read the CHM files in OS X and has no option to configure. Just double click a CHM file, and voila!
Chamonix is another software that can read CHM files. I have not tried this one since I used Chmox. One is enough but I’m pretty sure this one’s a good software too.
CHM files are merely nothing else but help information so there’s no need for complexities with software features. As long as it can read CHM files, you should be good to go.