Just execute the hh.exe HTML Help viewer with the name of the help file as the first parameter:
HH.exe is the HTML Help executable. It is located in the Windows directory does not require a path.
Note that topic names are referenced as Topic ID + .htm in all lower case characters. (The standard extension is .htm but this can be changed in .)
Opens the file myhelp.chm and displays the topic requestedtopic.htm. The "::/" in the parameter separates the requested topic (the html file name in the internal structure of the .chm file).
Opens the file myhelp.chm and displays the topic requestedtopic.htm and jumps to the topic anchor paragraph2.
HH -mapid 123456 myhelp.chm
Opens the file myhelp.chm and displays a topic referring to its help context number.