I don't always have an internet connection when I'm working in Houdini. Also, I'm hoping to find a method to get the docs onto my tablet, and allow for easy bookmarking, highlighting and notation.

Does the documentation exist in a location on a Mac where I can copy the files from directly, or is it only available online?

maybe this topic can help you :

http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=31801&highlight=Httrack [sidefx.com]