You can use the REST API for this. Check the 'REST API Explorer' on your source instance where you may find the available methods and the script examples.
For instance, you may get the list of incidents from the source instance with following Method:
GET https://instance.service-now.com/api/now/table/incident?sysparm_limit=1
Then you can use the ServiceNow script sample at your target instance as a scheduled job (check the code samples in the same REST API explorer window):
var request = new sn_ws.RESTMessageV2();
request.setEndpoint('https://instance.service-now.com/api/now/table/incident?sysparm_limit=1');
request.setHttpMethod('GET');
//Eg. UserName="admin", Password="admin" for this code sample.
var user = 'admin';
var password = 'admin';
request.setBasicAuth(user,password);
request.setRequestHeader("Accept","application/json");
var response = request.execute();
gs.log(response.getBody());
This is a sample script. You will have to update it to parse the JSON response from the webservice and map the data to your target table. Let me know if you need more help here.
