To start, login using one of your accounts at:
Amazon S3 HTTP Basic Auth Gateway
Point your test.example.com CNAME to relay.s3auth.com, and register the domain here. You will be able to access bucket's content in a browser with HTTP basic auth. Your bucket will be accessible using your Amazon IAM credentials and with custom user/password pairs in your .htpasswd file (similar to Apache HTTP Server).
For example, try http://maven.s3auth.com/ (with username s3auth and password s3auth). You will access content of Amazon S3 bucket maven.s3auth.com, which is not readable anonymously otherwise.