I would try the REST API ( PUT /persistence/items/{itemname} ) of openHAB.
Or have a look to Migrate your existing persistence data to InfluxDB ( it points to GitHub - CWempe/rest2influxdb ) which makes use of call to the influxdb server like
curl -i -XPOST -u $influxuser:$influxpw "http://$influxserver:$influxport/write?db=$influxdatbase" --data-binary @$i
to import data per item.