I'll list what I did below, but the docs site has a good step by step guide on this as well: https://docs.servicenow.com/bundle/tokyo-platform-administration/page/administer/field-administratio...
1. Create a custom table and make sure it extends from the Data Lookup Matcher Rules table
2. On the custom table, create 2 new fields: Assignment Group and Interaction Type. (My requirement was to assign an interaction to a particular group based on the interaction type, but you could swap this for Location. Just make sure you set the location field on your custom table as a reference field.)
3. Navigate to 'Data Lookup Definitions', click new and select 'Data Lookup Rule'
4. Give it a relevant name, select 'Interaction' as the source table, and your new custom table as the Matcher table. Tick the relevant box depending on when you want the rule to run. I selected 'Run on insert'. Then click Submit.
5. Go back into your new record and you should now see 2 related lists, Matcher Field Definitions and Setter Field Definitions.
6. Under Matcher Field Definitions, click 'New'.
7. For the source table field, select the field on the interaction that you want to match. In my scenario this was 'type' but for you this will be 'Location'
8. For the matcher table field, select the field on your custom table table that will hold the matching value. In my scenario this was 'Interaction type' but for you this will be your custom location field'
9. Click submit
10. Back on the data lookup record, under the 'Setter Field Definition' related list click New
11. For the source table field, select the Assignment group field
12. For the matcher table field, select the assignment group field from your custom table
13. Click submit
14. Now navigate back to your custom table record and click the 'Show List' related link
15. Click 'New'
16. On the new record select the Interaction type (for you this is location) and then select the assignment group you want it to go to.
17. Finally, create a new interaction record and then test that it goes to the assignment group you have set.
