How to install the Mods:
(Video below)

1) Open up %appdata%, if you don't know how to do this, start>run, then type in %appdata%
2) Browse to .minecraft/bin
3) Open up minecraft.jar with WinRAR or 7zip. WinRar Is my favourite (<!-- m --><!-- m -->)
4) Drag and drop the necessary files into the jar.
5) Delete the META-INF folder in the jar.
6) Run Minecraft, enjoy!

1) Go to Applications>Utilities and open terminal.
2) Type in the following, line by line:

cd ~
mkdir mctmp
cd mctmp
jar xf ~/Library/Application\ Support/minecraft/bin/minecraft.jar

3) Outside of terminal, copy all the files and folders into the mctmp directory.
4) Back inside terminal, type in the following:

jar uf ~/Library/Application\ Support/minecraft/bin/minecraft.jar ./
cd ..
rm -rf mctmp

5) Run Minecraft, enjoy!