If you haven’t done so already, configure the EC2 CLI tools. You can download the latest EC2 toolchain from here.
(It’s also available using homebrew “brew install ec2-api-tools”)
Now configure the environment variables:

export EC2_HOME=~/.ec2
export PATH=$PATH:$EC2_HOME/bin
export JAVA_HOME=$(/usr/libexec/java_home)
export AWS_ACCESS_KEY=
export AWS_SECRET_KEY=

Note: The Java path cannot be a symlink. It must be the actual path to the java home.

Test the EC2 CLI tools by running:

ec2-describe-regions