$ pip install httpie-api-auth
You should now see
$ http --help output.
$ http --auth-type=api-auth --auth='access_id:secret_key' example.org
As of version 0.3.0 of this library, only the new canonical string form introduced in api_auth 1.4 is supported. If you need to interact with services that have not yet upgraded to be compatible with this new scheme, you will need to use version 0.2.1 of this library to sign requests in a manner that those services will accept.