There are a few ways you could go about it,

1. Build a UI widget that POSTs to the /rest/v2/point-values endpoint.

[
  {
     "xid": "DP_Num_Example",
     "timestamp": 1557250438657,
     "dataType": "NUMERIC",
     "value": 123.456
  }
]

2. Encode the date and rate information into one or more points, then trigger a scripting data source which "Saves historic" to .set(value, timestamp) to the appropriate points. I may set an alphanumeric to 52.13~1557250438657 which is a context point that updates the context of a script which simply splits the string on ~ and turns it back to numbers.

Neither of these methods would cause point events to run currently (no websocket notification of the new value, , but the value would be available for recalculating meta point histories, for instance.