Amazon S3 Map to Windows Drive Letter

We are looking for a connectivity solution that integrates with Amazon S3 hosting. There will necessarily need to be two pieces to this: a website/service as well as a desktop application. The website must allow an admin to create a "company" with "users" inside of it all with separate logins/passwords. The admin will be able to connect a "company's" amazon s3 account using their amazon login/password. Then the users of the company can install a desktop application and it will map all of the directories that the admin has provided access to. This is a proof of concept at the moment, but it is understandably an extensive proof. Please submit your (or your firm's) expertise with Amazon. Must be written in C#/MSSQL