Windows 8 (or at least 8.1) doesn't seem to be too far off from the directions on that site.  If you're proficient enough to change an environment variable in Windows 7, chances are good you can figure it out on Windows 8(.1).  If you're not, chances are good you probably shouldn't :)

Either way, I think that these days giving instructions on how to set an environment variable is beyond the scope of the Python documentation.  We ought to just say "here's the environment variables that Python cares about, and here's what they do" and leave the instructions for setting them to other sites.  We might link to some site deemed to have good instructions, but keeping them inline means trying to keep them updated, which has apparently not gone well :)