I would ignore those instructions. Instead use the manual installer to install Flash. For details see Adobe Troubleshoot Flash Player installation guide

Firefox is telling me up upgrade my Adobe Flash Player due to a security issue. When I download the update i receive a window telling me "The procedure entry point Set DIIDirectoryW could not be located in the dynamic link library KERNEL32.dll"

rmctoledo, See Flash Plugin - Keep it up to date and troubleshoot problems and http://kb.mozillazine.org/Flash#Installing_or_updating_Flash for help installing the Flash plugin. If you need more help, please ask your question again by starting a new thread in the support forum, https://support.mozilla.org/questions/new so that we can better help you.

(This thread is over a year old and belongs to a Windows Vista user who was using Firefox 3.6. When you start your own thread we can see information about your own system.)