Free Pascal includes a CHM read / write library (no dependencies), and SVN versions also contain a basic CHM command-line compiler. The license is the same as the rest of the FPC library, LGPL with a static binding exception, so perfect for commercial use.
I think it's pretty easy to port to Delphi.
A somewhat outdated package page for this package
http://wiki.freepascal.org/chm
The package was originally developed for the FPC fpdoc library documentation toolkit. (Documentation is generated at night in some cases, and all FPC / Lazarus servers are Unix)
Marco van de voort
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