How to manually install cab files for Internet Explorer?

1. regsrv32 /s C:\Windows\SysWOW64\pluginname.ocx
2. Expand the .cab file contents
3. Then install the .inf file
4. Open a command prompt
5. Navigate to C:\Windows\System32
6. Type the name of the ocx file and press Enter

Apparently this registers the ocx. Not sure how since 1. seems to imply you actually need to run a registration tool.

Reference:
http://www.ehow.com/how_6190504_manually-install-active-internet-explorer.html