Git-s3 is a cool tool for deploying a git repo to a S3 bucket.  The tool depends on php and a program called composer. Since I couldn’t find composer installation instructions for Windows, I decided to jot down the following:

Composer Installation on Windows

Install php (if it’s not installed already)

I recommend using Chocolatey:

$ cinst php

Close your cmd window, then open a command window. type:
$ php
and make sure you can access the php command

Download composer (note the -k flag to work around the SSL certificate validation on Windows)
$ curl -sS -k https://getcomposer.org/installer | php

Install git-s3
$ php composer.phar composer global require schickling/git-s3:dev-master

Add git-s3 to PATH. Modify your environment PATH when git-s3 was installed — for example, mine was installed under \AppData\Roaming\Composer\vendor\bin

git-s3 is now ready for use. Go ahead and configure
$ git-s3 config

I opened a Github pull request,  you can view the updated composer doc on Github.