Most people don't sign help packages. They just ship & install the .mshc file and that get's indexed at install time (as recommended by MS).
But signing means you can install silently.
If you are going to sign your help then the .mshc help file needs to be put inside a .cab file, and the .cab file signed. Microsoft .cab packages contain a .mshc & a .mshi index file. By including an Index your help does not need to be ripped (index) at install time. A faster install.
For HV 1.0 index can be fished out of the store:
If you don't use mshcMigrate, just grab the .mshi index file (from the help data store) and add the .mshc and .mshi to a .cab file. It's import that the .cab, .mshc and .mshi (if included) all have the same base file name. Otherwise install will fail.
Note #1: Whenever mshcMigrate Migrate/Update commands run they generate a .cab file of the same name. It places into the .cab file the .mshc help file and an index (.mshi) file if one exists with the same name (in the same folder as the .mshc/.cab etc).
Note #2: The instructions above are for HV 1.0 (VS 2010 RTM help). The .mshi in the store is only suitable for HV 1.x. For HV 1.1 and HV 2.x you should generate .mshi using HelpIndexer.exe from the the Windows 8 ADK.
HelpIndex.exe is a Microsoft utility for generating a HV 1.1 & HV 2.0 compatible .mshi file. Currently HelpIndexer.exe command line utility is only available by downloading the Windows 8 ADK. Once the ADK is installed you will find HelpIndexer.exe in the folder:C:\Program Files\Windows Kits\8.0\Assessment and Deployment Kit\Deployment and Imaging Tools\HelpIndexer\
Example command line: helpindexer.exe /i <mshc name>.mshc /o /v <vendor name>/store