Odoo-S3 uses boto to talk to Amazon. You will need to install it on the host running Odoo.
This module was written for Odoo v9.0 and is only tested with this particular version. There is no warranty the addon will work for other releases.
In order to use Odoo-S3 you will need to switch to "Developer mode" and define a new system parameter as follow
ir_attachment.location ---> s3://<Your-AWS-Access-Key-ID>:<Your-AWS-Secret-Key>@<Your-S3-Bucket-name>
Pull requests are welcome. The code is fairly short and easy to understand. All the magic happens in models.py where the regular model ir_attachment is extended.