Where to place the Pointer Permissions Json?

On docs.parseplatform.org/rest/guide/ we can see the explanation of pointer permissions and an example, but where is this supposed to be placed, and what is the endpoint?

{
    "<SENDER_USER_ID>": {
        "read": true,
        "write": true
    },
    "<RECEIVER_USER_ID>": {
        "read": true
    }
}

The easiest way to setup the CLP is through the Parse Dashboard. There is an option in the upper right side of your dashboard when browsing a class. Have you tried?