Not that I am aware of. There are three properties in the portal.properties that you override with respect to allowing access using the s3 bucket key, secret and bucket name. In terms of who can read / write, you would need to manage that using the role permissions for the document library. If you import your user groups from the directory store that you use for authentication, and then associate those groups to a liferay role, that should let you use you IAM config to control access to the dl.
