Many, many people have said that hacks work in singleplayer, and they have all told me to read the instructions when i asked them how to use it. I've read it many times
 Here it is:
INSTRUCTIONS

    To start up the game, simply download our client wrapper package below, extract it,
    put the official minecraft.jar (which you downloaded from the official site as per
    the above notice) into the lib folder and then execute run.bat. The external client
    application will prompt you for your login details and then allow you to select from
    the available servers, or enter your own server link to connect.

Ok, now I know how to use  it in multiplayer. Thanks...

HOW THE F**K DO I USE IT IN SINGLEPLAYER????? Please answer me... I'm starting to get... angry...