This is still an experimental feature and not part of the release. Please refer to the nightly builds if you wish to try it.
A simple HTTP POST request is used to send the input graph and retrieve its the layouted version. You can just perform your own request to the correct URL and pass all required information. However, as we might change internal APIs we recommend you to use the (very small) wrapper implementations we provide for a specific language. We do not provide a wrapper for each language, feel free to write your own and contact us so we can add it to the list below.