Step 1. Download them. http://aws.amazon.com/developertools/351
Step 2. Set Java path in your .bash_profile:
export JAVA_HOME=/System/Library/Frameworks/JavaVM.framework/Home/
Step 3. test Java path is correct:
$JAVA_HOME/bin/java -version
Step 4. set ec2 path in your .bash_profile:
export EC2_HOME=/Users/breck/Downloads/ec2-api-tools-1.4.4.1
export PATH=$PATH:$EC2_HOME/bin