How to localize a .chm file? Firstly, there is an interesting post about this topic on venTAJAmarketing blog. Secondly, I decompiled the file using HTML Help Workshop application and used CatsCradle CAT tool to translate the extracted .html files and others. CatsCradle is inexpensive compared with some other tools.
Other tools for help files > Sisulizer Enterprise, Lingobit.