what I posted was a bit of a short version.
First, you will need to find out the name registered for the extension, which is the default value in HKEY_CLASSES_ROOT.html (for me it is htmlfile).
Then HKEY_CLASSES_ROOT\htmlfile\shell\printto\command will contain the command.
If the default value for HKEY_CLASSES_ROOT.html is e.g. HKEY_CLASSES_ROOT\ChromeHTML on your machine, the path for the command would be HKEY_CLASSES_ROOT\ChromeHTML\shell\print to\command
Of course using the other utility might be easier/just as good, I mainly added the info in case anybody else comes across this and needs a way to fix the registry entries.