Setting externalId via SCIM

Is it possible to set all the values returned in the list users via SCIM? For example, how do I set the externalId?

SCIM 2.0 API reference

Hi @browngb, the "externalId" key is set automatically when the user is created from a third party application, it is always null if the user is created from within our organization. Unfortunately, the put request does not allow us to update that key. However, if we need additional custom attributes, we could make a put request and add key value pairs inside of the "metadata" key.