To install MayaMan just extract the directory where you want.

  ie: C:\mayaman\

Then set these environment variables:

  MAYA_PLUG_IN_PATH - ie: C:\mayaman\plugins\8.5\
  MAYA_SCRIPT_PATH - ie: C:\mayaman\mel\

Run Maya and from the plugins manager load MayaMan,
you can check autoload if you want.

That's all, enjoy it!
   