Yes, the codec pack is available for installation using the package on the official website. I have downloaded a package and installed it in offline mode (network adapter was disabled) and Internet connection wasn't needed.
First, access the download page below (I recommend FULL version to be downloaded since it's most comprehensive) and then launch it from the download folder.
Download page: http://www.codecguide.com/download_k-lite_codec_pack_full.htm
As you can see in the image below, I have reached Install phase without needing Internet.