How can I create a Salesforce CRM Instance by passing the token directly?

Via our POST /instances endpoint. See the following example payload:

{
"element": {
  "key": "sfdc"
   },
  "configuration": {
    "oauth.api.key": "<Insert_Client_ID>",
    "oauth.api.secret": "<Insert_Client_Secret>",
    "oauth.user.refresh_token": "<Insert_Refresh_Token"
   },
  "tags": [
    "<Tags>"
   ],
  "name": "PassTokenTest",
  "externalAuthentication": "initial"
}